AP Computer Science Principles

Abstraction

removing unnecessary details to focus on the important parts of a problem or system.

Algorithm

a step-by-step set of instructions to solve a problem or perform a task.

Analog data

continuous data that changes smoothly over time (like sound or light).

API

a set of rules that let programs communicate with each other (stands for Application Programming Interface).

Argument

a value passed to a procedure when it is called (can be a variable, constant, or expression).

Arithmetic operators

symbols used in math operations: +, −, *, /, MOD (remainder).

Assignment statement

stores a value in a variable using ← (e.g. x ← 5 means store 5 in x).

Authentication

verifying the identity of a user or system before allowing access.

Bandwidth

the amount of data that can be sent over a network in a set time.

Bias

unfair preference or discrimination in code or data that affects outcomes.

Binary number system

a way computers store and process data using only 0s and 1s.

Binary search

a fast search method that repeatedly checks the middle of a sorted list.

Bit

the smallest unit of data in a computer, either 0 or 1.

Boolean values

values that are only true or false.

Byte

a group of 8 bits.

Certificate Authority (CA)

trusted group that issues certificates to verify secure websites.

Citizen scientist

someone who helps scientists collect or analyze data (often online).

Clarity

how easy it is to understand and follow a program or code.

Classifying data

sorting data into categories to help find patterns or trends.

Cleaning data

fixing or removing errors, duplicates, or inconsistencies in a dataset.

Code segment

a small part of code from a bigger program.

Code statement

a single action in code that the computer runs.

Collaboration

working with others to complete a project or solve a problem.

Comments

notes in code for humans to read (ignored by the computer).

Computer virus

harmful code that spreads and can destroy or steal data.

Computing device

any tool that runs programs (like phones, laptops, or smartwatches).

Computing network

a group of connected devices that share data.

Computing system

a group of devices and programs working together for a task.

Concatenation

joining strings together to make a new one (like "Hi" + "Zain" = "HiZain").

Condition

a test in a program that checks if something is true or false.

Creative Commons Licensing

allows creators to give permission for others to use their work in specific ways.

Crowdfunding

raising money from many people (usually online) to support a project.

Crowdsourcing

getting help or ideas from a large group of people online to solve problems or contribute.

Cybersecurity

protecting devices, programs, and networks from digital attacks.

Data abstraction

using a list or data structure to manage values without needing to know how they're stored.

Data mining

analyzing large datasets to find useful patterns or insights.

Data stream

a continuous flow of data sent in packets over a network.

Debugging

finding and fixing errors in a program.

Decidable problem

a problem that can always be solved with a yes/no answer by an algorithm.

Decision problem

a problem that only needs a yes or no answer.

Decryption

converting encrypted (coded) data back into readable form.

Digital data

data shown as separate values (not continuous) like 0s and 1s.

Digital divide

the gap between people who have access to technology and those who don’t.

Distributed computing system

a system where many computers work together on different parts of a problem.

Efficiency

how well an algorithm uses resources like time or memory.

Element

a single item in a list (accessed using its index).

Encryption

turning readable data into a secret code to protect it.

Event-driven programming

a program that runs certain code when a specific event (like a click) happens.

Expression

a combination of values and operations that gives one result (like x + 5).

Fault-tolerant

a system that keeps working even if some parts fail (like the Internet).

Filtering data

choosing specific data based on conditions to analyze.

Heuristic

a shortcut solution that isn’t perfect but works well enough, especially for hard problems.

Hypertext Transfer Protocol (HTTP)

rules for transferring web pages on the Internet.

Hypertext Transfer Protocol Secure (HTTPS)

a secure version of HTTP that encrypts your data (used when shopping online).

Incremental development process

building a program piece by piece and testing as you go.

Information

data that has been processed to give meaning or help decision-making.

Intellectual property

anything you create using a computer that you legally own.

Internet Protocol (IP) address

a unique number given to your device when it connects to the Internet.

Iterative

repeating steps in a loop until a condition is met.

Iterative development process

coding, testing, and refining over and over to improve your program.

Keylogging

malicious software that secretly records what you type and sends it to someone else.

Library

a collection of prewritten code you can import and use in your own program.

Linear search

checking each item in a list one by one to find a match.

Lists

a collection of values stored in one variable

Logic error

the program runs, but the output is wrong due to incorrect logic.

Logical operators

used in conditions:

AND (both must be true),

OR (at least one must be true),

NOT (reverses true/false).

Lossless data compression

reduces file size without losing any data — the original can be perfectly restored.

Lossy data compression

reduces file size by permanently removing some data — the original can't be fully restored.

Malware

software designed to damage or steal data from a device.

Metadata

data about data (e.g., author name, creation date).

Modularity

breaking a program into smaller parts (modules) that each do a specific task.

Modulus

a math operation that returns the remainder of a division (ex: 10 MOD 3 = 1).

Multifactor authentication

using more than one method to confirm identity (ex: password + text message code).

Open access

data that’s free to use without restrictions.

Open source

software that’s freely available to use, modify, and share.

Optimization problem

a problem where you’re trying to find the best or most efficient solution.

Overflow error

happens when a number is too big to be stored in the given memory space.

Packets

chunks of data sent over a network with info about where they’re going and how to reassemble them.

Parallel computing system

multiple computers or processors work on different parts of a task at the same time.

Parameter

a variable that gets its value from an argument when a procedure is called.

Patterns in data

trends or repetitions in data that help you make predictions or decisions.

PII (Personally Identifiable Information)

info that can identify you (like your name, address, ID, or email).

Phishing

tricking users into sharing private info through fake emails or websites.

Plagiarism

using someone else's work without giving credit or getting permission.

Procedural Abstraction

hiding the details of how a procedure works — just use the input/output and not worry about the internal code.

Procedure

a reusable block of code that performs a specific task — runs only when called.

Program

a complete set of code that performs a specific function.

Program behavior

how a program works when it runs and how users interact with it.

Program documentation

written explanation of what the program does and how to use or understand it.

Program input

data sent into a program (like from a keyboard, file, or sensor).

Program output

data the program produces (like text on a screen, a printed page, or stored data).

Proprietary software

software that is owned by a company, with restrictions on how it can be used, modified, or shared.

Pseudocode

a simplified way to plan a program using plain language and programming-like structure.

Public key encryption

uses two keys — a public one to encrypt and a private one to decrypt

Redundancy

having backup systems or pathways in case one part of a network or system fails.

Relational database

stores data in tables with rows and columns and connects data across tables using relationships.

Return

a command in a procedure that sends back a value to wherever the procedure was called.