APCSP Exam Vocabulary

Abstraction

Hiding complexity behind a simpler interface so you only see what's necessary

Procedural abstraction

Using a named procedure to hide the implementation details of a task

Data abstraction

Using a list or variable to represent multiple related values under one name

Algorithm

A finite set of step-by-step instructions designed to accomplish a specific task

Sequencing

Executing code statements in order, top to bottom, one after another

Selection

A control structure (IF/ELSE) that chooses which code runs based on a condition

Iteration

A repeating portion of an algorithm — a loop that runs until a condition is met

Syntax error

A mistake in the code's grammar that prevents the program from running at all

Logic error

A mistake in the algorithm that causes the program to run but produce wrong results

Runtime error

An error that occurs while the program is running, causing it to crash

Test case

A specific input paired with the expected output used to verify a program works

Edge case

An extreme or boundary input value used to test a program's limits

Iterative development

A repeated cycle of design, code, test, and revise used to build programs

Program purpose

The problem being solved or the creative goal being pursued by the program

Program function

What the program actually does step-by-step during execution

Collaboration

Working with others to design or develop a program, which reduces errors and bias

Bit

A single binary digit — either 0 or 1 — the smallest unit of digital data

Byte

A group of 8 bits

Binary

A base-2 number system that uses only the digits 0 and 1

Overflow error

Occurs when a value is too large for the available bits, causing it to wrap around incorrectly

Roundoff error

Imprecision that occurs when a decimal number cannot be represented exactly in binary

Lossless compression

Reduces file size without losing any data — the original can be perfectly reconstructed

Lossy compression

Reduces file size by permanently discarding some data — cannot be undone

Metadata

Data that describes other data, such as a photo's timestamp, GPS location, or file size

Data collection

Gathering raw data from sources like sensors, surveys, or observations

Data visualization

Using charts or graphs to identify patterns and trends in large data sets

Correlation

A relationship where two variables tend to change together, but one does not cause the other

Causation

A relationship where one variable directly causes a change in another variable

Analog data

Continuous, smoothly varying data such as sound waves or temperature readings

Digital data

Discrete data represented as binary values (0s and 1s)

Sampling

Converting analog data to digital by measuring values at regular intervals

Variable

A named storage location in a program that holds a value which can change

List

An ordered sequence of elements accessed by their index position, starting at index 1 in AP pseudocode

Procedure

A named group of programming instructions that can have parameters and return values

Parameter

A variable in a procedure's definition that accepts input values when the procedure is called

Argument

The actual value passed to a procedure when it is called

Return value

The output that a procedure sends back to the part of the program that called it

Boolean expression

An expression that evaluates to either true or false

Traversal

Accessing each element in a list one by one, typically using a loop

Linear search

Checking each element one at a time — works on any list, sorted or unsorted

Binary search

Repeatedly splitting a sorted list in half to find a value — faster but requires a sorted list

Reasonable time

Algorithm runtime grows polynomially (n, n-squared, n-cubed) as input grows — practical

Unreasonable time

Algorithm runtime grows exponentially (2 to the n, n!) — becomes impractical for large inputs

Undecidable problem

A problem for which no algorithm can always produce a correct answer — proven impossible

Heuristic

An approach that finds a good-enough solution quickly when finding the optimal solution is too slow

Simulation

A program that models a real-world system to make predictions or test hypotheses

MOD

The remainder operator — 17 MOD 5 equals 2. Used to check divisibility (n MOD 2 = 0 means even)

Internet

The global system of interconnected networks that communicate using TCP/IP protocols

World Wide Web

An application that runs on top of the internet using HTTP/HTTPS and web browsers

Packet

A small chunk of data sent independently across a network and reassembled at the destination

IP address

A unique numerical identifier assigned to each device on a network

DNS

Domain Name System — translates human-readable URLs into IP addresses

TCP

Transmission Control Protocol — ensures packets are delivered reliably and in the correct order

IP (protocol)

Internet Protocol — handles the addressing and routing of packets to their destination

HTTP

HyperText Transfer Protocol — the protocol used to transfer web pages

HTTPS

HTTP Secure — adds TLS/SSL encryption to HTTP for secure data transmission

Bandwidth

The maximum amount of data that can be transmitted per second over a network connection

Latency

The delay between sending data and it arriving at its destination

Fault tolerance

The ability of a system to continue operating even when some components fail

Parallel computing

Running multiple tasks simultaneously on different processors to speed up a program

Sequential computing

Running tasks one after another in order, where each step may depend on the previous

Router

A device that forwards data packets toward their destination across a network

PII

Personally Identifiable Information — any data that can identify a specific individual such as name, SSN, or email

Digital divide

The unequal access to technology and the internet across different populations or regions

Algorithmic bias

Unfair outcomes produced by an algorithm due to biased training data or flawed design

Encryption

The process of scrambling data so only authorized parties with the correct key can read it

Public key cryptography

An encryption system using two keys — a public key to encrypt and a private key to decrypt

Phishing

A cyberattack using fake emails or websites to trick users into revealing passwords or personal data

Malware

Malicious software designed to damage or gain unauthorized access to a computer system

Ransomware

A type of malware that encrypts a victim's files and demands payment to restore access

DDoS

Distributed Denial of Service — flooding a server with traffic from many sources to make it crash

Multi-factor authentication

A security method requiring two or more types of verification to log in to an account

Cookie

A small file stored on your device by a website to track your activity and preferences

Crowdsourcing

Using contributions from a large number of people online to complete a task or gather data

Creative Commons

A licensing system that allows creators to share their work with specific usage conditions

Open source

Software whose source code is publicly available for anyone to view, modify, and distribute

Copyright

The legal right giving creators exclusive control over how their original work is used

Citizen science

A form of crowdsourcing where volunteers help collect or analyze scientific data