AP CSP vocabulary

The AP Computer Science Principles exam introduces a wide range of topics across the field of computer science.

This review highlights terminology from the big ideas that are new to most students and includes links to more in-depth explanations.

Overflow: Error that results when the number of bits is not enough to represent the number (like a car’s odometer “rolling over”). Learn more in Number limits, overflow, and round-off.

Round-off: Error that results when the number of bits is not enough to represent the number with full precision (like using 3 digits to represent $\pi$‍ as 3.14). Learn more in Number limits, overflow, and round-off.

Metadata: Data about data, like descriptive information about a file or a row in a database. Learn more in Files.

Lossless: Compressing data in a way that preserves all data away and allows full recovery of the original. Learn more in File compression.

Lossy: Compressing data in a way that discards some data and makes it impossible to recover the original. Learn more in Lossy vs. lossless compression.

Sequencing: The sequential execution of steps in an algorithm or code in a program (like steps in a recipe). Learn more in The building blocks of algorithms.

Selection: A Boolean condition to determine which of two paths are taken in an algorithm or program. Learn more in The building blocks of algorithms and Conditionals: if, else, and Booleans.

Iteration: The repetition of steps in an algorithm or program for a certain amount of times or until a certain condition is met. Learn more in The building blocks of algorithms and Repetition.

Linear search : An algorithm that iterates through each item in a list until it finds the target value. Learn more in Measuring an algorithm's efficiency.

Binary search: An algorithm that searches a sorted list for a value by repeatedly splitting the list in half. Learn more in Measuring an algorithm's efficiency.

Reasonable time: A run time for an algorithm that doesn't increase faster than a polynomial function of the input size (like $10n$‍, $n^2$‍, etc). An unreasonable run time would increase superpolynomially (like $2^n$‍ or $n!$‍). Learn more in Categorizing run time efficiency.

Heuristic: A technique that helps an algorithm find a good solution in a hard problem (like always walking toward the north star when you are stuck in a forest). Learn more in Using heuristics.

Undecidable: A problem that is so logically difficult, we can’t ever create an algorithm that would be able to answer "yes or "no" for all inputs (like the halting problem). Learn more in Undecidable problems.

API: Application Programming Interface, a library of procedures and a description of how to call each procedure.

Bit rate: The number of bits that are transferred per second, typically measured in Kbps, Mbps, Gbps. Learn more in Transporting bits over wires.

Bandwidth: The maximum bit rate of a network connection. Learn more in Transporting bits over wires.

Latency: The time elapsed between sending a message and the recipient receiving the message. Learn more in Transporting bits over wires.

IP (Internet Protocol): The protocol that determines how to address nodes on the network (with IP addresses) and how to route data from one node to a destination node (using routers). Learn more in IP addresses and Internet routing protocol.

TCP (Transmission Control Protocol): The protocol that is in charge of splitting data into small packets and reliably transmitting the packets to a destination. Learn more in Transmission Control Protocol (TCP).

DNS (Domain Name System): A hierarchical system of name servers that are responsible for mapping domain names (like khanacademy.org) to IP addresses. Learn more in Domain Name System.

TLS (Transport Layer Security): A protocol that adds a layer of encryption to TCP/IP connection, necessary for sending data privately across the internet. Learn more in Transport Layer Security.

Symmetric encryption: A technique for encrypting data where the same key is used to both encrypt and decrypt data. Learn more in Symmetric encryption techniques.

Public key encryption: An asymmetric encryption technique that uses different keys for encrypting versus decrypting data. Learn more in Public key encryption.

HTTP (Hypertext Transfer Protocol): The protocol that powers the web, used to request webpages from servers and submit form data to servers. Learn more in Hypertext Transfer Protocol.

HTTPS (HTTP Secure): The combination of the HTTP and TLS protocols to create secured connections to websites. Learn more in HTTP Secure.

Cookie: A small amount of text that tracks information about a user visiting a website. Learn more in Privacy on the web.

Distributed Denial-of-Service attacks (DDoS): A cyber attack that floods a server with an enormous number of requests, so that it does not have the resources to service normal user requests. Learn more in Computer malware and attacks.

Virus: A type of computer malware that hides within the source code of another program. Learn more in Computer malware and attacks.

Antivirus software: An application that attempts to detect and remove computer malware downloaded to a computer. Learn more in Computer malware and attacks.

Firewall: A system that monitors incoming and outgoing network traffic to a computer and filters out unwanted traffic. Learn more in Computer malware and attacks.

Phishing: An attack where a user is tricked into revealing private information, often via a deceptive email. Learn more in Phishing and password attacks.

Cloud computing: The practice of using a network of computers hosted on the Internet to store, manage, and process data, instead of a local server or personal computer. Users may use cloud computing via web applications (like Google Drive) and programmers may use cloud computing to run their applications (like Amazon Web Services). Mentioned in Chat, video conferencing, and collaborative software.

Moore’s Law: A prediction that the number of transistors on a chip doubles every two years, correlating to an increased speed in computers. Learn more in Scientific computing and simulation.

Peer-to-peer networks: A system where one user’s computer connects through the Internet to another user’s computer without going through an intermediary “centralized” computer to manage the connection. Mentioned in Copyright, DRM, and the DMCA.

Crowdsourcing: A model in which many online users combine efforts to help fund projects, generate ideas, or create goods or services (like Wikipedia). Learn more in Crowdsourcing, crowdfunding, and open innovation.

Citizen science: Crowdsourcing for science! The participation of volunteers from the public in a scientific research project (like collecting rain samples or counting butterflies). Learn more in Global participation in science.

Creative Commons: An alternative to copyright that allows people to declare how they want their artistic creations to be shared, remixed, used in noncommercial contexts, and how the policy should propagate with remixed versions. Learn more in Creative commons and open source.

Open Access: A policy that allows people to have access to documents (like research papers) for reading or data (like government datasets) for analysis. Learn more in Sharing science research online.

Digital divide: The idea that some communities or populations have less access to computing than others, typically due to limitations of internet speed or computer hardware access.