AP Computer Science Principles Vocabulary

Abstraction

The process of reducing complexity by focusing on essential details while hiding irrelevant information; a general concept derived from specific instances.

Similar definitions: generalization, simplification

Example: "Using a function to perform a repeated task is an example of          because it hides the implementation details."

Access Control

A security technique that regulates who or what can view or use resources in a computing environment.

Example: "Requiring a password to open a file is a form of         ."

Algorithm

A finite set of step-by-step instructions designed to solve a specific problem or accomplish a task.

Similar definitions: procedure, process, method

Example: "A recipe for baking bread can be compared to an          because it provides precise, ordered steps."

Algorithmic Efficiency

A measure of the computational resources (time and memory) an algorithm requires relative to the size of its input.

Example: "Binary search has better          than linear search for sorted data."

Analog Data

Data represented by continuously varying physical quantities, as opposed to discrete digital values.

Example: "The temperature reading on a mercury thermometer is          because it changes continuously."

Analog-to-Digital Conversion

The process of converting continuous analog signals into discrete digital values that a computer can process.

Example: "Recording a voice through a microphone involves          so the sound can be stored digitally."

API (Application Programming Interface)

A set of defined rules and protocols that allows different software applications to communicate and share data with each other.

Example: "The weather app uses a third-party          to retrieve current forecast data from a meteorological service."

Application

A program or group of programs designed for end users to perform specific tasks on a device.

Similar definitions: app, software application, program

Example: "A word processor is a common          used to create and edit text documents."

Argument

A value passed to a function when it is called, corresponding to a parameter in the function's definition.

Similar definitions: parameter value, input value

Example: "In the function call add(3, 5), the numbers 3 and 5 are the         s passed to the function."

Artifact

Any computing output created by a person using a computer, including programs, images, audio, video, presentations, or web pages.

Similar definitions: computational artifact, computing artifact

Example: "The mobile app the students built for their project is a computing         ."

ASCII

American Standard Code for Information Interchange; a character encoding standard that assigns numerical values to letters, digits, and symbols.

Example: "In         , the capital letter A is represented by the decimal value 65."

Authentication

The process of verifying the identity of a user, device, or system before granting access to resources.

Example: "Entering a username and password is a basic form of         ."

Automation

The use of computer programs to perform tasks that would otherwise require human effort, increasing speed and efficiency.

Example: "         allowed the factory to produce thousands of items per hour without manual assembly."

Bandwidth

The maximum rate of data transfer across a network connection, typically measured in bits per second (bps).

Example: "Streaming high-definition video requires greater          than sending a text email."

Beneficial and Harmful Effects

The positive and negative consequences — intended and unintended — that computing innovations have on individuals, society, and the world.

Example: "Social media has         : it helps people connect globally (beneficial) but can spread misinformation rapidly (harmful)."

Bias

A systematic error or prejudice in data, algorithms, or computing systems that produces unfair or skewed outcomes.

Similar definitions: computing bias, algorithmic bias

Example: "If a hiring algorithm was trained mostly on data from male applicants, it may have          against women."

Big Data

Extremely large datasets that are too complex for traditional software to process, requiring special tools to analyze and extract insights.

Example: "Scientists used          techniques to analyze billions of social media posts to study trends in public opinion."

Binary

A base-2 number system using only the digits 0 and 1, which forms the foundation of all digital data representation.

Example: "Computers store all information in          because transistors can only be in an on (1) or off (0) state."

Binary Search

An efficient search algorithm that repeatedly divides a sorted list in half to locate a target value, running in O(log n) time.

Example: "         is much faster than linear search when looking for a name in a sorted phone book."

Bit

The smallest unit of digital data, representing a single binary value of either 0 or 1.

Example: "A single          can represent a light switch being either off (0) or on (1)."

Bit Rate

The number of bits processed or transmitted per unit of time, typically measured in bits per second (bps).

Example: "Streaming high-definition video requires a higher          than streaming standard-definition video."

Boolean

A data type that has only two possible values: true or false, used to control program flow through conditions.

Example: "The variable isLoggedIn is a          value that is either true or false."

Boolean Expression

An expression that evaluates to either true or false, often used in conditionals and loops.

Example: "The statement x > 10 is a          that determines whether a number exceeds ten."

Boolean Operator

A logical operator (AND, OR, NOT) used to combine or modify Boolean expressions in conditions and searches.

Example: "The search engine used the          AND to find results that contained both 'climate' and 'change'."

Browser

A software application used to access, retrieve, and display content from the World Wide Web.

Similar definitions: web browser

Example: "Chrome, Firefox, and Safari are all examples of a web         ."

Brute Force

A problem-solving method that tries every possible solution systematically until the correct one is found.

Example: "Trying all possible password combinations is a          approach that works but is very slow."

Bug

An error or flaw in a program that causes it to produce incorrect results or behave unexpectedly.

Similar definitions: error, defect, fault

Example: "The program crashed every time the user entered a negative number because of a          in the code."

Byte

A unit of digital information consisting of 8 bits, capable of representing 256 different values (0–255).

Example: "A single character in standard ASCII encoding is stored as one         ."

Call

The act of invoking a function or procedure in a program, causing its instructions to execute.

Similar definitions: invoke, execute

Example: "When the program reaches the line printResult(), it makes a          to the printResult function."

Central Processing Unit (CPU)

The main processor of a computer that executes instructions, performs calculations, and coordinates the activities of all other hardware components.

Example: "The          executes millions of instructions per second to run the operating system and applications."

Cipher

An algorithm used to perform encryption or decryption, transforming data into an unreadable form and back.

Example: "The Caesar          shifts each letter in a message by a fixed number of positions in the alphabet."

Ciphertext

The encrypted, unreadable version of data that results from applying an encryption algorithm to plaintext.

Example: "The message appeared as meaningless          to anyone who intercepted it without the decryption key."

Client

A device or program that requests services or resources from a server over a network.

Example: "Your web browser acts as a          when it requests a webpage from a remote server."

Client-Server Model

A network architecture in which client devices request resources or services from centralized server computers.

Example: "When you check your email online, your device and the mail service communicate using the         ."

Cloud Computing

The delivery of computing services—including storage, processing, and software—over the internet rather than on local hardware.

Example: "Storing photos on Google Drive instead of a local hard drive is an example of         ."

Code

Instructions written in a programming language that a computer can interpret and execute.

Similar definitions: source code, program code

Example: "The developer wrote          in Python to automate the data analysis process."

Code Reuse

The practice of using existing code (functions, libraries, or modules) in new programs to save development time and reduce errors.

Example: "By writing general-purpose functions, the developer enabled          across multiple projects."

Collaboration

The practice of working jointly with others to design, develop, and improve computing artifacts or solve problems.

Example: "         between team members helped them find and fix bugs more quickly than working alone."

Computational Artifact

Something created as the result of a computational process, such as a program, image, video, audio file, or presentation.

Similar definitions: artifact, computing artifact

Example: "The infographic the students made using design software is a         ."

Computational Thinking

A problem-solving approach that involves decomposing problems, recognizing patterns, abstracting details, and designing algorithms.

Example: "Applying         , the student broke a complex scheduling problem into smaller, manageable sub-problems."

Computer

An electronic device that processes data according to a set of instructions (programs) to produce a desired result.

Example: "A smartphone is a portable          capable of running many different applications."

Computer Network

A system of two or more computing devices connected together to share resources and communicate.

Similar definitions: network

Example: "The school's          allows every classroom computer to share the same printer."

Computing Device

A physical device that can run a program, including computers, tablets, smartphones, and embedded systems.

Example: "A smart thermostat is a          that runs software to regulate home temperature."

Computing Innovation

A new or improved computing artifact, technique, or system that has a significant effect on society, the economy, or culture.

Example: "The development of GPS navigation was a          that transformed how people travel."

Computing System

A group of hardware and software components working together to process, store, and communicate data.

Example: "A laptop with its operating system, apps, and hardware components forms a complete         ."

Conditional

A programming construct that executes different code blocks based on whether a condition evaluates to true or false.

Similar definitions: if statement, selection statement, branching

Example: "The          statement checks if a user's age is over 18 before granting access to the site."

Confidentiality

The principle that sensitive data should only be accessible to those authorized to view it, a key goal of cybersecurity.

Example: "Encryption helps ensure the          of medical records stored in the cloud."

Constant

A named value in a program that does not change during execution.

Example: "The programmer defined PI as a          with the value 3.14159 so it would not be accidentally changed."

Cookie

A small piece of data stored on a user's device by a web browser, used to remember information about the user across sessions.

Example: "The website saved a          on the user's browser to keep them logged in."

Copyright

A legal protection that grants creators exclusive rights to reproduce, distribute, and adapt their original works.

Example: "Using someone's photograph without permission may violate their         ."

Creative Commons

A set of standardized licenses that allow creators to share their work with specific permissions for public use.

Example: "The musician released her song under a          license so others could remix it for free."

Creative Development

The iterative process of designing and building computing innovations through collaboration, testing, and revision.

Example: "The app went through several rounds of          as the team refined the user interface based on feedback."

Crowdsourcing

The practice of obtaining input, information, or services from a large distributed group of people, often via the internet.

Example: "Wikipedia relies on          to build and maintain its encyclopedia articles."

Cryptography

The practice and study of techniques for securing communication and data by transforming it into an unreadable form.

Example: "Modern internet security depends on          to protect sensitive financial transactions."

Cybersecurity

The practice of protecting computer systems, networks, and data from unauthorized access, damage, or attack.

Example: "The company hired a          expert to find and patch vulnerabilities in their software."

Data

Raw facts, values, or observations that can be processed, analyzed, or stored by a computer.

Example: "The survey collected          from 1,000 students about their daily screen time."

Data Abstraction

The use of a collection or structure (such as a list or dictionary) to manage multiple related values under one name.

Example: "Storing all student names in a single list is a form of         ."

Data Cleaning

The process of detecting and correcting (or removing) corrupt, inaccurate, or irrelevant records from a dataset before analysis.

Example: "Before running the analysis, the researcher performed          to remove duplicate entries and fix formatting errors."

Data Compression

The process of reducing the size of data by encoding information more efficiently, making storage and transmission faster.

Example: "         allows a music file to be stored in a fraction of the space of the original recording."

Data Mining

The process of discovering patterns, correlations, and insights in large datasets using statistical and computational methods.

Example: "The retailer used          to discover that customers who buy diapers often also buy beer on Friday evenings."

Data Type

A classification that specifies what kind of value a variable holds, such as integer, string, Boolean, or list.

Example: "The variable age has the          integer because it stores whole numbers."

Data Visualization

The graphical representation of data (charts, graphs, maps) to help people understand patterns, trends, and insights.

Example: "A bar chart is a simple form of          that makes it easy to compare values across categories."

Database

An organized collection of structured data stored electronically, designed for efficient retrieval and manipulation.

Example: "The hospital stored patient records in a          that doctors could query to find treatment histories."

Debugging

The process of identifying, analyzing, and correcting errors (bugs) in a program.

Example: "After hours of         , the programmer finally found the off-by-one error causing the crash."

Decomposition

The process of breaking a complex problem or system into smaller, more manageable sub-problems or components.

Example: "The team used          to divide the large app project into separate tasks: UI design, database setup, and API integration."

Decryption

The process of converting encrypted (ciphertext) data back into its original readable form (plaintext).

Example: "Only the recipient with the correct private key could perform          on the secret message."

Digital Data

Information represented as discrete binary values (0s and 1s) that can be stored and processed by computers.

Example: "A scanned photograph becomes          when converted into a grid of pixels stored as binary values."

Digital Divide

The gap between individuals, communities, or countries that have access to modern information technology and those that do not.

Example: "Students in rural areas without broadband internet face a          compared to students in cities."

Disinformation

False information deliberately spread to deceive people, often amplified by digital platforms and social media.

Example: "The          campaign spread fabricated news stories to mislead voters before the election."

Distributed Computing

A computing model in which tasks are divided and processed across multiple networked computers simultaneously.

Example: "The SETI@home project used          to analyze radio telescope data on millions of volunteers' computers."

DNS (Domain Name System)

A hierarchical naming system that translates human-readable domain names (like google.com) into IP addresses computers use to communicate.

Example: "When you type a URL into your browser, the          converts that name into the server's numeric IP address."

Documentation

Written explanations and comments that describe what a program does, how it works, and how to use it.

Example: "The          for the library explained each function's parameters and return values."

Domain Name

A human-readable label (such as example.com) that identifies a location on the internet and maps to an IP address via DNS.

Example: "The          makes it easier for users to remember web addresses instead of numeric IP addresses."

Encryption

The process of encoding data so it can only be read by someone with the correct key or decryption method.

Example: "The bank uses          to protect credit card numbers transmitted over the internet."

End-to-End Encryption

A communication method where only the communicating users can read the messages, preventing interception by third parties including service providers.

Example: "Messaging apps that use          ensure that even the app company cannot read users' private chats."

Environmental Impact

The effects of computing technology on the natural environment, including energy use, electronic waste, and carbon emissions from data centers.

Example: "The          of streaming millions of videos daily includes significant electricity consumption in server farms."

Error

A mistake in a program that prevents it from running correctly; can be a syntax error, runtime error, or logic error.

Similar definitions: bug, fault

Example: "The program produced an          when it tried to divide a number by zero."

Event

An action or occurrence detected by a program, such as a mouse click, key press, or timer expiration, that triggers a response.

Example: "Clicking the submit button triggers an          that causes the form data to be sent to the server."

Event-Driven Programming

A programming paradigm where the flow of the program is determined by events such as user actions, sensor outputs, or messages.

Example: "Most graphical user interfaces rely on          to respond to button clicks and keyboard input."

Expression

A combination of values, variables, operators, and function calls that evaluates to a single value.

Example: "The          (x + y) * 2 produces a numeric result based on the current values of x and y."

Fault Tolerance

The ability of a system to continue functioning correctly even when one or more of its components fail.

Example: "The internet was designed with          so that traffic can be rerouted if a connection goes down."

Firewall

A network security system that monitors and controls incoming and outgoing network traffic based on predefined security rules.

Example: "The company's          blocked unauthorized attempts to access its internal servers from outside the network."

Flowchart

A diagram that represents the steps and decision points of an algorithm or process using standardized symbols and arrows.

Example: "The programmer drew a          to plan the logic of the login system before writing any code."

For Loop

A control flow statement that iterates a specific number of times or over each element in a collection.

Example: "The          iterated over each item in the shopping list and printed its name."

Function

A named block of reusable code that performs a specific task and can be called from anywhere in a program.

Similar definitions: procedure, method, subroutine

Example: "The programmer wrote a          to calculate the area of a circle so the formula didn't need to be repeated."

Global Impact

The worldwide effects — social, economic, cultural, or environmental — that computing innovations have on people and societies.

Example: "Social media has had a significant          by changing how billions of people communicate and share information."

Hacker

A person who uses technical skills to gain unauthorized access to computer systems, or (in a positive sense) someone who creatively solves technical problems.

Example: "A malicious          broke into the company's database and stole customer information."

Hardware

The physical components of a computer system, including the processor, memory, storage devices, and input/output devices.

Example: "The keyboard, monitor, and hard drive are all examples of computer         ."

Heuristic

A problem-solving approach that uses practical techniques to find a good-enough solution when an optimal solution is impractical to compute.

Example: "GPS navigation uses a          to find a fast route without checking every possible path."

Hexadecimal

A base-16 number system using digits 0–9 and letters A–F, commonly used to represent binary data in a more compact form.

Example: "Web colors are often written in         , such as #FF5733 for a shade of orange."

HTML (HyperText Markup Language)

The standard markup language used to create and structure content on the World Wide Web.

Example: "The developer used          tags like <h1> and <p> to structure the text on the webpage."

HTTP (HyperText Transfer Protocol)

The foundational protocol used by the World Wide Web to define how messages are formatted and transmitted between browsers and servers.

Example: "When you visit a website, your browser sends an          request to the server to retrieve the page."

HTTPS

An extension of HTTP that uses encryption (TLS/SSL) to secure data transmitted between a browser and a web server.

Example: "Online banking sites use          to protect users' financial information from interception."

Hyperlink

A reference in a digital document that links to another document or location when clicked, enabling web navigation.

Example: "Clicking the          on the homepage took the user to the product page."

Identity Theft

The fraudulent acquisition and use of another person's private information, typically for financial gain.

Example: "The criminal used stolen personal data to commit          and open credit cards in the victim's name."

Impact of Computing

The effects—both intended and unintended, beneficial and harmful—that computing innovations have on individuals, society, and the world.

Example: "Studying the          includes examining how social media affects mental health."

Index

A numeric position identifying an element within a list or string, typically starting at 1 (in AP CSP pseudocode) or 0 (in most languages).

Example: "In the list [10, 20, 30], the element at          2 is 20."

Infinite Loop

A loop that never terminates because its exit condition is never reached, causing a program to run indefinitely.

Example: "Because the counter variable was never updated, the program entered an          and had to be force-quit."

Information

Data that has been processed, organized, or structured so that it has meaning and is useful for decision-making.

Example: "Raw temperature readings become useful          when they are averaged to show a monthly climate trend."

Input

Data provided to a program or computing device for processing, such as keyboard input, sensor readings, or file data.

Example: "The user's typed text is the          that the spell-check program processes."