AP Computer Science Principles Vocabulary

2D array

A 2D array (two-dimensional array) is an array of arrays, organized in rows and columns like a grid. It is commonly used to represent matrices, game boards, or image pixel data.

Example: "A programmer representing a Tic-Tac-Toe board stores the game state in a          with 3 rows and 3 columns, where each cell holds either 'X', 'O', or an empty string."

Abstraction

Abstraction is the process of reducing complexity by focusing on the main idea. By hiding details irrelevant to the question at hand, abstraction allows one to focus on a manageable number of aspects of a problem.

Example: "When designing a navigation app, developers use          to focus on calculating the shortest route rather than worrying about how each road's asphalt composition was laid."

Abstraction (computing definition)

Abstraction in computing is the process of managing complexity by hiding unnecessary details while exposing only the essential features needed to solve a problem. It ranges from hardware abstraction up to high-level software concepts.

Example: "A programmer writing a function to sort a list uses abstraction by calling a built-in sort procedure without needing to understand the underlying quicksort or merge sort implementation."

Abstraction (data representation)

Data representation abstraction means that the same information can be represented in multiple equivalent ways. For example, the number 13 can be represented as binary 1101, decimal 13, or hexadecimal D.

Example: "The color red in a digital image can be expressed through data representation abstraction as the decimal value 255, the binary sequence 11111111, or the hexadecimal value FF, all referring to the same maximum red intensity."

Abstraction layer

An abstraction layer is one level in a hierarchy of abstractions, where each layer hides the complexity of lower layers. Examples range from transistors up through logic gates, machine code, OS, and application software.

Example: "When a Python programmer calls a file-reading function, they are working at a high         , unaware of the lower-level disk controller instructions and transistor signals that physically retrieve the data."

Access control

Access control regulates who can access resources in a computing system. It is implemented through authentication (verifying identity) and authorization (determining permitted actions).

Example: "A school's learning management system uses          to allow students to view assignments and submit work, while restricting grade-editing privileges to authenticated teachers only."

Accessibility (computing)

Accessibility in computing is the design of technology to be usable by people with a wide range of abilities and disabilities. Accessible design removes barriers that might prevent people from using computing tools.

Example: "A web developer improves accessibility by adding alt text to all images and ensuring keyboard navigation works correctly, allowing screen readers to convey the site's content to visually impaired users."

Algorithm

An algorithm is a finite set of instructions that accomplishes a specific task.

Example: "The step-by-step process a search engine uses to rank web pages by relevance—checking keywords, evaluating link counts, and sorting results—is an example of an         ."

Algorithm efficiency

Algorithm efficiency describes how time or memory usage scales with input size. Problems solvable in polynomial time are considered efficient; those requiring exponential time are generally impracticaltical for large inputs.

Example: "A linear search through one million records may take one million comparisons in the worst case, while a binary search on the same sorted data requires at most about 20, demonstrating why          matters at scale."

Algorithmic bias

Algorithmic bias occurs when an algorithm produces systematically unfair outcomes, often due to biased training data or design assumptions. Algorithmic bias can perpetuate or amplify societal inequalities.

Example: "A hiring algorithm trained primarily on resumes from male candidates may exhibit          by ranking female applicants lower, perpetuating gender inequality in the hiring process."

Analog data

Analog data have values that change smoothly, rather than in discrete intervals, over time.

Example: "The continuous fluctuations in air pressure produced by a person's voice are         , which a microphone must convert into discrete digital samples before a computer can process them."

AND operator

The AND operator evaluates to true only when both operands are true. If either operand is false, the result is false. Example: (x > 0) AND (x < 10) is true only when x is between 0 and 10.

Example: "In a program that checks whether a user is eligible for a student discount, the condition (age >= 13) AND (age

APPEND procedure

In AP CSP pseudocode, APPEND(aList, value) increases the length of aList by 1 and places value at the end of the list.

Example: "After prompting a user to enter a test score, the program uses APPEND(scoreList, newScore) to add the entered value to the end of scoreList, growing the list by one element."

Application program interfaces (APIs)

Application program interfaces (APIs) are specificationsforhowtheproceduresina library behave and can be used.

Example: "A weather app retrieves current temperature data by making calls to a weather service's API, following the documented specifications for how to send requests and interpret the returned data."

Argument

Arguments specify the values of the parameters when a procedure is called.

Example: "When the procedure calculateArea is called as calculateArea(5, 8), the values 5 and 8 are          that get passed into the parameters width and height respectively."

Array

An array is a collection of elements stored at contiguous memory locations, all of the same data type. Arrays are accessed using indices and are called lists in AP CSP pseudocode.

Example: "A program tracking the daily high temperatures for a week stores the seven values in an         , accessing each temperature using its index from 0 to 6."

Artificial intelligence

Artificial intelligence (AI) is the simulation of human intelligence by computer systems, including learning, reasoning, and problem-solving. AI enables computing innovations that respond adaptively to input.

Example: "The spam filter in an email service uses          to learn patterns from millions of flagged messages and automatically classify new incoming emails as spam or legitimate."

ASCII

ASCII (American Standard Code for Information Interchange) is a character encoding standard that uses 7 bits to represent 128 characters, including letters, digits, punctuation, and control characters.

Example: "When a user types the letter 'A' on a keyboard, the computer internally stores it using          as the value 65, which in binary is 1000001."

Assignment operator

An assignment operator sets the value of a variable. In AP CSP pseudocode, the assignment operator is represented as the left arrow (a

Authentication

Authentication is the process of verifying the identity of a user, device, or system before granting access. Methods include passwords, biometrics (fingerprint, face recognition), and security tokens.

Example: "When a student logs into an online exam portal,          verifies their identity by checking the submitted username and password against stored credentials before allowing access."

Authorization

Authorization determines whether an authenticated user has permission to access specific resources or perform specific actions. Authentication establishes identity; authorization grants privileges.

Example: "After a hospital employee is authenticated by logging in,          determines that a nurse can view patient records but cannot modify prescription information, a privilege reserved for physicians."

Automation

Automation uses technology to perform tasks with minimal human intervention. Computing has enabled automation across many industries, changing employment patterns and creating new types of work.

Example: "Automated checkout systems in grocery stores use computing to scan barcodes, calculate totals, and process payments without requiring a human cashier, reducing labor costs while changing the nature of retail work."

Automation bias

Automation bias is the tendency to over-rely on automated systems, accepting their outputs without sufficient critical evaluation. This can lead to errors when automated systems make mistakes.

Example: "A pilot who accepts every altitude adjustment suggested by the autopilot without cross-checking the instruments is exhibiting         , which can be dangerous if the automated system malfunctions."

Bandwidth

Bandwidth is the maximum amount of data that can be sent in a fixed amount of time on a computer network, usually measured in bits per second.

Example: "A fiber-optic connection with a          of 1 gigabit per second can download a 1 GB file in about 8 seconds, far faster than a 10 Mbps connection that would take over 13 minutes."

Bandwidth (data transfer)

Bandwidth is the maximum rate of data transfer across a network path, measured in bits per second. Higher bandwidth allows more data to be transmitted in a given time period.

Example: "During a live-stream concert, the platform requires sufficient bandwidth to transmit high-definition video data to thousands of simultaneous viewers without buffering or quality degradation."

Base case

A base case is the condition in a recursive algorithm that stops the recursion and returns a value without making another recursive call. Without a base case, recursion would continue indefinitely.

Example: "In a recursive function that computes the factorial of a number, the          is when n equals 0 or 1, at which point the function returns 1 instead of calling itself again."

Bias

Bias is not eliminated by simply collecting more data.

Example: "A facial recognition system trained mostly on lighter-skinned faces may perform poorly on darker-skinned faces, and simply collecting more of the same skewed data will not eliminate that         ."

Bias in data

Bias can be introduced into data by the type or source of data being collected. Bias is not eliminated by simply collecting more data.

Example: "A survey about internet usage conducted only among smartphone owners introduces          because it excludes populations without smartphone access, skewing results toward more connected demographics."

Big data

Big data refers to extremely large and complex datasets that require advanced computational tools to process and analyze. Analysis of big data can reveal patterns and insights not visible in smaller datasets.

Example: "Genomics researchers analyze          by processing the DNA sequences of millions of patients to identify genetic markers associated with specific diseases, a task impossible without large-scale computational tools."

Binary

Binary is a base-2 number system that uses only the digits 0 and 1 to represent numbers. All digital data is ultimately stored and processed as binary values.

Example: "All images, videos, and text stored on a computer are ultimately represented in         , with every pixel color, character, and audio sample encoded as a sequence of 0s and 1s."

Binary addition

Binary addition adds two binary numbers using rules: 0+0=0, 0+1=1, 1+0=1, 1+1=10 (write 0, carry 1). Binary addition is fundamental to how computers perform arithmetic in hardware.

Example: "When adding the binary numbers 0110 and 0101,          produces 1011, following the carry rules just as decimal addition carries values when a column sum reaches 10."

Binary search

Binary search is an algorithm that starts at the middle of a sorted data set of numbers and eliminates half of the data with each comparison. Binary search is often more efficient than sequential/linear search when applied to sorted data.

Example: "To find a student's name in an alphabetically sorted list of 1,000 entries, a          compares the target name to the middle entry and eliminates half the list with each step, finding the name in at most 10 comparisons."

Binary to decimal conversion

Binary to decimal conversion translates a binary number to its decimal equivalent by multiplying each bit by its positional value (power of 2) and summing the results. Example: 1011 = 8+0+2+1 = 11.

Example: "To convert the binary number 1101 to decimal, you compute 1×8 + 1×4 + 0×2 + 1×1 = 13, demonstrating how each bit position represents a power of 2."

Binary tree

A binary tree is a hierarchical data structure where each node has at most two children (left and right). Binary search trees enable efficient searching, insertion, and deletion operations.

Example: "A program managing a sorted contact list stores names in a          so that searches, insertions, and deletions can be performed efficiently by traversing left or right branches based on alphabetical comparisons."

Bit

Bit is shorthand for binary digit and is either 0 or 1.

Example: "A single          can store whether a light switch is on or off, but combining 8          into a byte allows 256 different values to be represented, such as every possible ASCII character."

Bit manipulation

Bit manipulation refers to acting directly on individual bits of binary data using bitwise operations (AND, OR, XOR, NOT, shift). It is used in low-level programming and cryptography.

Example: "A graphics program uses          with a bitwise AND operation to isolate the blue channel from a pixel's 24-bit color value, extracting just the 8 bits that represent blue intensity."

Bit rate

Bit rate is the number of bits processed or transmitted per unit of time, usually measured in bits per second (bps). Higher bit rate generally means better quality for audio and video.

Example: "A music streaming service offers songs at 320 kbps, meaning the          is 320,000 bits per second, producing higher audio fidelity than the 128 kbps option at the cost of more data usage."

Bits

Bits are grouped to represent abstractions.

Example: "When a computer stores a color image, groups of          are used together to represent abstractions like pixel colors, with 24          typically encoding over 16 million possible color values."

Boolean

Boolean refers to a data type with only two possible values: true or false.

Example: "A variable named isLoggedIn holds a          value that is true when a user has authenticated and false when they have not, controlling which parts of the interface are displayed."

Boolean expression

A Boolean expression is an expression that evaluates to either true or false. Boolean expressions use relational operators (=, not equal, >,

Boolean logic

Boolean logic is the branch of algebra using variables with only two possible values (true/false). The primary operations are AND (both true), OR (at least one true), and NOT (reverse), forming the foundation of computing.

Example: "Computer processors perform arithmetic using circuits built on         , where AND, OR, and NOT gates manipulate individual bits to carry out every calculation the CPU performs."

Boolean value

A Boolean value is either true or false.

Example: "After checking whether a list is empty, a function returns a         —true if the list contains no elements, false if it contains at least one—which the calling code uses to decide the next step."

Botnet

A botnet is a network of computers infected with malware and remotely controlled by an attacker. Botnets are used for distributed denial-of-service attacks, sending spam, or mining cryptocurrency.

Example: "Attackers deployed a          of 500,000 infected home routers to flood a major website with traffic, executing a distributed denial-of-service attack that made the site unreachable for several hours."

Byte

A byte is 8 bits. Bytes are the standard unit of digital storage and memory size. Common multiples include kilobyte (1,024 bytes), megabyte (1,024 KB), and gigabyte (1,024 MB).

Example: "A plain-text file containing the word 'Hello' takes up approximately 5          of storage because each ASCII character is represented using one         ."

Cache memory

Cache memory is a small, fast type of memory that stores frequently accessed data to reduce access time to slower main memory. Caches improve program performance.

Example: "A processor repeatedly accessing the same lookup table during a simulation stores that data in          so it can retrieve values in nanoseconds rather than waiting hundreds of nanoseconds for slower RAM."

Certificate authority

Certificate authorities issue digital certificates that validate the ownership of encryption keys used in secure communications and are based on a trust model.

Example: "When a browser connects to a banking website over HTTPS, it contacts a          to verify that the digital certificate presented by the site is legitimate and has not been forged."

Ciphertext

Ciphertext is data that has been encrypted using an algorithm and key, making it unreadable without the corresponding decryption key. Converting ciphertext back to plaintext is called decryption.

Example: "After a user's password is encrypted with a symmetric key algorithm, it becomes          that appears as meaningless characters to anyone who intercepts it without the decryption key."

Citizen science

Citizen science is a form of research collaboration where members of the public contribute data or analysis using personal devices. Computing technology enables large-scale citizen science projects.

Example: "The SETI@home project used          by allowing volunteers worldwide to donate their computers' idle processing time to analyze radio telescope data for signs of extraterrestrial intelligence."

Clarity and readability

Clarity and readability are important considerations when expressing an algorithm in a programming language.

Example: "A programmer uses descriptive variable names like totalStudentCount instead of x to improve the          of the code, making it easier for teammates to understand and maintain."

Cleaning data

Cleaning data is a process that makes the data uniform without changing their meaning (e.g., replacing all equivalent abbreviations, spellings, andcapitalizationswiththesameword)..

Example: "Before analyzing survey responses, a data scientist performs          by standardizing all entries of 'U.S.A.', 'US', and 'United States' to a single consistent value so the country is counted correctly."

Client

A client is a computer or application that requests services, resources, or data from a server. In client-server architecture, clients initiate requests and servers respond with data or services.

Example: "When a user opens a browser and requests a webpage, the browser acts as a         , sending an HTTP request to the web server and waiting to receive and display the returned HTML content."

Cloud computing

Cloud computing is the delivery of computing services including servers, storage, databases, networking, and software over the Internet rather than on local hardware, enabling flexible and scalable access to resources.

Example: "A small startup uses          to host its application on rented servers, scaling up resources during peak traffic periods and avoiding the large upfront cost of purchasing physical hardware."

Code segment

A code segment is a collection of program statements that is part of a program.

Example: "The          that calculates a student's letter grade—containing the conditional statements that check numeric score ranges—can be reused anywhere in the program where grading logic is needed."

Code statement

A code statement is a part of program code that expresses an action to be carried out.

Example: "The line total

Code tracing

Code tracing is the process of manually following the execution of a program step by step to determine its output or identify errors, without running the program on a computer.

Example: "To verify that a sorting algorithm works correctly, a student performs          by writing out the values of each variable after every iteration, confirming the list is reordered as expected."

Collaboration

Collaboration is the practice of working with others to solve problems and create computing innovations. Collaboration is crucial when developing computing innovations because having multiple perspectives offers opportunities to improve the design of innovations.

Example: "The team developed a more inclusive accessibility feature by practicing         —bringing together perspectives from designers, developers, and users with disabilities to identify requirements no single person had considered."

Comments

Comments are a form of program documentation written into the program to bereadbypeopleanddonotaffecthowa program runs.

Example: "A programmer adds          at the beginning of a complex loop to explain that it iterates through only the even-indexed elements, helping a future developer understand the logic without re-analyzing the code."

Compiler

A compiler translates an entire program written in a high-level language into machine code or an intermediate representation before execution. Compiled programs generally run faster than interpreted ones.

Example: "Before a C++ program can run, a          translates the entire source code into machine language instructions specific to the target processor, catching syntax errors in the process."

Computational problem

A computational problem is a task that can be addressed through the use of an algorithm. Computational problems range from simple (sorting a list) to complex (route planning) to undecidable (halting problem).

Example: "Determining whether a given number is prime is a          because it can be solved by an algorithm that systematically tests divisors up to the square root of the number."

Computational thinking

Computational thinking is a problem-solving approach involving decomposition (breaking problems into smaller parts), pattern recognition, abstraction (identifying essential information), and algorithm design.

Example: "Designing a school scheduling system requires         : decompose it into sub-problems like room assignment and conflict detection, recognize patterns from past schedules, abstract away irrelevant details, and then develop an algorithm."

Computer network

A computer network is a group of interconnected computing devices capable of sending or receiving data.

Example: "The devices in a school—student laptops, teachers' desktop computers, and shared printers—are all part of a          that allows them to share files and access the Internet through a common router."

Computer virus

A computer virus is a malicious program that can copy itself and gain access to a computer inanunauthorizedway.Computervirusesoften attach themselves to legitimate programs and start running independently on a computer.

Example: "A student accidentally downloaded a          disguised as a game file; the virus attached itself to other programs on the laptop and spread to a shared drive, corrupting several documents."

Computing artifact

A computing artifact is something created using computing tools, such as a program, digital image, audio recording, video, or presentation. Computational artifacts are the products of computational work.

Example: "The mobile app a student created to track daily water intake is a         —a product built using computational tools that serves a practical purpose."

Computing bias

Computing bias occurs when results produced by algorithms or data reflect existing societal biases, often due to biased training data or flawed algorithm design.

Example: "A loan-approval algorithm that relies on zip code data may exhibit          by systematically denying applicants from historically redlined neighborhoods, replicating historical discrimination in an automated system."

Computing device

A computing device is a physical artifact that can run a program.

Example: "A Raspberry Pi is a low-cost          capable of running programs that control sensors, displays, and motors, making it popular for educational robotics projects."

Computing innovation

A computing innovation includes a program as an integral part of its function. A computing innovation can be physical (e.g., self-driving car), nonphysical computing software (e.g., picture editing software), or a nonphysical computing concept (e.g., e-commerce).

Example: "A GPS navigation app is a          because a program is integral to its function—processing satellite signals, running routing algorithms, and displaying turn-by-turn directions in real time."

Computing system

A computing system is a group of computing devices and programs working together for a common purpose.

Example: "An automated traffic management network is a          in which sensors, traffic lights, servers, and control software all work together to reduce congestion across a city."

Concatenation

Concatenation is the operation of joining two or more strings end-to-end to produce a new, longer string.

Example: "A program builds a personalized greeting by using          to join 'Hello, ' with the user's name variable and '!' to produce the string 'Hello, Maria!'."

Concurrent computing

Concurrent computing involves multiple computations occurring during overlapping time periods. It includes parallel computing (simultaneous execution) and distributed computing (execution across multiple devices).

Example: "A video rendering application speeds up processing through          by splitting the work across eight processor cores that each render different frames of the video simultaneously."

Conditional statement

A conditional statement uses a Boolean expression to determine which block of code executes. In AP CSP pseudocode, an IF/ELSE construct executes the first block if the condition is true and the second block otherwise.

Example: "A program uses a          to display 'Pass' if a student's score is 60 or higher and 'Fail' otherwise, executing different code blocks depending on the evaluation of the Boolean expression."

Content delivery network

A content delivery network (CDN) is a geographically distributed network of servers that delivers web content to users based on their geographic location, reducing latency and improving load times.

Example: "When users around the world stream a popular video, a          serves the video from servers located in each user's region, reducing buffering caused by long-distance data travel."

Cookies (web)

Cookies are small pieces of data stored by a website on a user's device. They track user sessions, preferences, and browsing behavior, which can be used for targeted advertising or to enhance user experience.

Example: "An online store uses cookies to remember items a user added to their shopping cart during a previous visit, so the cart still contains those items when the user returns the next day."

Copyright

Copyright is legal protection giving creators exclusive rights to their original works, including software, text, images, and music. Copyright applies automatically when a work is created.

Example: "A student who copies original code from a developer's GitHub repository and submits it as their own project work without permission may be infringing         , since the code is automatically protected the moment it is created."

Creative Commons

Creative Commons is a public copyright license that enables the free distribution of an otherwise copyrighted work. This is used when the content creator wants to give others the right to share, use, and build upon the work they have created.

Example: "A photographer releases their portfolio under a          license so educators can freely use the images in class presentations without needing to request individual permission."

Creative Commons license

A Creative Commons license allows creators to grant others rights to share, use, and build upon their work under specified conditions, balancing protection of rights with access to information.

Example: "A teacher finds a YouTube video released under a          that allows remix and redistribution, so she legally edits clips from it into her own instructional video."

Crowdsourcing

Crowdsourcing is the practice of obtaining input or information from a large number of people via the Internet.

Example: "OpenStreetMap is built through         , where millions of contributors worldwide submit GPS traces, road names, and location data from their own devices to create a collaboratively maintained global map."

Cybercrime

Cybercrime refers to criminal activities carried out using computers or the Internet, including hacking, identity theft, financial fraud, and distribution of malware. Cybercrime has significant personal and economic impacts.

Example: "Stealing a victim's credit card numbers by installing malicious software that captures keystrokes on their computer is a form of          that can result in significant financial harm and federal criminal charges."

Cybersecurity

Cybersecurity is the practice of protecting computing systems, networks, and data from unauthorized access, attacks, damage, and theft. It involves technical measures as well as user behavior and policies.

Example: "A company strengthens its          posture by encrypting sensitive customer data, training employees to recognize phishing emails, and requiring multi-factor authentication for all system logins."

Data

Data are the values stored and used by programs. Data can come in many forms such as numbers, text, images, and more.

Example: "The          stored in a fitness tracker—including step counts, heart rate readings, and GPS coordinates—can be analyzed to provide users with personalized health recommendations."

Data abstraction

Data abstraction allows programs to work with collections of data using high-level operations (like list procedures) without knowing details of how the data is stored or managed internally.

Example: "By using a list and its built-in procedures like INSERT and REMOVE, a programmer manages a collection of student names through          without needing to know how the list allocates memory internally."

Data aggregation

Data aggregation combines data from multiple sources to create more comprehensive datasets. Aggregating data can reveal information about individuals that was not apparent from separate data points alone.

Example: "Combining a user's location history, purchase records, and browsing data through          can reveal sensitive details about their daily routine and personal habits, even if each data source seems harmless alone."

Data compression

Data compression reduces the number of bits needed to represent data.

Example: "Streaming services use          to reduce video file sizes before transmission so that high-definition content can be delivered over limited bandwidth connections without sacrificing too much visual quality."

Data integrity

Data integrity refers to the accuracy, consistency, and reliability of data throughout its lifecycle. Error detection and correction mechanisms help maintain data integrity during transmission and storage.

Example: "A network protocol uses checksums to verify         , detecting whether any bits in a transmitted packet were flipped during transmission and requesting a retransmission if errors are found."

Data mining

Data mining is the process of analyzing large datasets to discover patterns, correlations, and insights. Computing tools enable data mining that would be impracticaltical to perform manually.

Example: "Retailers apply          to years of purchase transaction records to discover that customers who buy baby products also frequently purchase wine, enabling targeted cross-promotional marketing campaigns."

Data parallelism

Data parallelism involves applying the same operation simultaneously to multiple data elements across multiple processors, commonly used in scientific computing and machine learning.

Example: "Training a neural network is accelerated through          by splitting a large batch of training images across hundreds of GPU cores that each compute gradient updates simultaneously."

Data structure

A data structure is a way of organizing and storing data in a computer so it can be accessed and modified efficiently. Common data structures include lists, stacks, queues, trees, and graphs.

Example: "A program that needs to process tasks in the order they arrive uses a queue          to ensure the first task added is always the first task removed and executed."

Data type

A data type is a classification that specifies the kind of value a variable can hold and what operations can be performed on it. Common data types include integer, floating-point, string, Boolean, and list.

Example: "Declaring a variable as a string          instead of an integer prevents a program from accidentally performing arithmetic on a phone number like '555-1234', which would produce meaningless results."

Data visualization

Data visualization is the graphical representation of data using charts, graphs, maps, and other visual formats to help people understand patterns, trends, and relationships within data.

Example: "Scientists studying climate change use          techniques such as heat maps and trend line graphs to communicate decades of temperature measurements in a form that policymakers can quickly understand."

Data-driven decision making

Data-driven decision making uses data analysis to inform choices. Computing tools enable processing of large datasets to discover patterns and insights that guide decisions in business, science, and government.

Example: "A public health department uses          by analyzing hospital admission records and vaccination rates to determine which neighborhoods should receive additional vaccine distribution resources."

Database

A database is an organized collection of structured data managed by a database management system (DBMS). Databases allow efficient storage, retrieval, and manipulation of large amounts of data.

Example: "A hospital stores patient records in a relational          so that doctors can query by patient ID, date of visit, or diagnosis code to quickly retrieve relevant medical history."

Debugging

Debugging is the process of identifying and fixing errors (bugs) in a program. Errors may be syntax errors (violating language rules), logic errors (incorrect algorithm), or run-time errors (occurring during execution).

Example: "After noticing that a program always outputs the wrong total, a developer uses          to add print statements that reveal a logic error—the loop was summing values from index 1 instead of index 0."

Decimal

Decimal is the base-10 number system used in everyday life, which uses digits 0-9 to represent values. Computers ultimately store all numbers in binary but can display them in decimal.

Example: "Although the computer stores the number 42 internally as the binary value 101010, the program displays it in          as '42' because that representation is far more intuitive for human users."

Decimal to binary conversion

Decimal to binary conversion translates a decimal number to binary by repeatedly dividing by 2 and recording remainders. The binary number is the remainders read in reverse order.

Example: "To store the decimal number 25 in a computer, it must be converted to binary: dividing repeatedly by 2 yields remainders 1,0,0,1,1, which when read in reverse gives the binary representation 11001."

Decision problem

A decision problem is a problem with a yes/no answer (e.g., is there a path from A to B?).

Example: "Determining whether a graph contains a Hamiltonian cycle—a path that visits every vertex exactly once—is a classic          with a yes or no answer, and it is considered computationally difficult to solve efficiently."

Decomposition

Decomposition is breaking a complex problem into smaller, more manageable sub-problems. It is a fundamental component of computational thinking that makes large problems tractable.

Example: "A team building a social media app uses          to break the project into smaller modules: user authentication, post creation, newsfeed display, and notifications, each developed and tested independently."

Decryption

Decryption is the process of decoding the data.

Example: "When a recipient receives an encrypted message, their device uses the appropriate private key to perform         , converting the unreadable ciphertext back into the original plaintext message."

Denial-of-service attack

A denial-of-service (DoS) attack attempts to make a computing resource unavailable by overwhelming it with traffic or requests. A distributed DoS (DDoS) attack uses many computers simultaneously.

Example: "During a product launch, attackers flooded a retailer's website with millions of fake requests in a         , consuming all server resources and preventing legitimate customers from completing purchases."

Digital certificate

A digital certificate validates the ownership of encryption keys used in secure communications and is issued by a certificate authority.

Example: "When a browser displays a padlock icon for a website, it has validated the site's         —issued by a trusted certificate authority—confirming that the encrypted connection is with the legitimate server."

Digital citizenship

Digital citizenship is the responsible and ethical use of technology. It encompasses online safety, privacy protection, cybersecurity awareness, digital literacy, and respecting intellectual property.

Example: "A student practicing good          cites the sources of images used in a school presentation, avoids sharing classmates' personal information online, and uses strong unique passwords for every account."

Digital data

Digital data can be represented as a finite number of binary values.

Example: "Unlike the continuous audio waves captured by a vintage vinyl record,          on a CD represents the same music as a finite sequence of binary values, sampled at discrete intervals of time."