AP Computer Science Principles Lecture Notes

Vocabulary terms and definitions related to AP Computer Science Principles, including internet architecture, security, algorithms, and development processes.

The Internet

A computer network that uses open protocols to standardize communication.

Computing Device

A physical object that can run a program, such as computers, tablets, cell phones, and smart sensors.

Computing System

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

Computer Network

An interconnected computing system that is capable of sending or receiving data.

World Wide Web

A collection of interlinked website documents that can be viewed using a web browser.

HTML

HyperText Markup Language; used for writing most web pages.

HTTP

HyperText Transfer Protocol; used by browsers to interpret HTML instructions for web page formatting.

ARPANET

An early form of the Internet developed in 1969 with a speed of $56\,kbps$.

Router

A computer or machine that passes information from one network to another.

Hypertext

Invented in 1989, it allows links to connect different parts of an electronic document or different documents.

IETF

The Internet Engineering Task Force; a standards organization responsible for the technical standards of the Internet protocol suite (TCP/IP).

ISPs

Internet Service Providers; companies that sell Internet access to homes and institutions.

The Cloud

Storing data somewhere on the Internet where the storage location is managed by a service provider (e.g., Google, Dropbox, Amazon).

Bandwidth

The maximum amount of data that can be sent in a fixed amount of time, measured in $bits\,per\,second$ for digital data.

DNS

Domain Name System; translates domain names like www.example.com into IP addresses, acting like the phonebook of the internet.

Path

A sequence of directly connected computing devices that connect a sender to a receiver.

Routing

The process of finding a path from sender to receiver.

Scalability

The ability of the Internet to keep working as it grows.

Redundancy

The inclusion of back-up elements in case one part fails, such as carrying an extra tube for a flat tire.

Fault Tolerance

The ability of a system to work around problems, such as running a bike with tubeless tires that still functions after a small puncture.

Protocol

A set of rules that specify the behavior of a system.

IP Address

A unique number assigned to each device on a computer network.

Packet

A small chunk of data and metadata (information about the data) passed through the Internet as a data stream.

Packet Switching

The Internet sends information in short bursts rather than long continuous strings.

IP (Internet Protocol)

A protocol that transmits packets from one IP address to another, allowing computers to simulate a direct connection.

TCP

Transmission Control Protocol; divides data into packets, ensures reliable transmission by tracking received packets, resending lost ones, and reassembling them in order.

UDP

User Datagram Protocol; a lightweight, fast transport protocol that detects corrupt data but does not address lost or out-of-order packets.

Malware

Software designed to harm or take partial control over a computer.

Keylogging

Type of malware that records every key pressed by a user.

Computer Virus

A type of malware that spreads and infects other computers by attaching to legitimate programs.

Firewall

A security system that controls the connections between a computer/network and the outside world.

Phishing

A security attack where the victim is tricked into giving up personal information or downloading malware.

DDoS Attack

Distributed Denial of Service; uses a virus to flood a server with requests so users are denied service.

Rogue Access Point

A wireless access point that gives unauthorized access to a secure network.

HTTP Cookie

A small amount of text that helps a website track information about a user and personalize their experience.

Citizen Science

Scientific research conducted by distributed individuals who contribute data using their own computing devices.

Crowdsourcing

The general term for using the Internet to get a large number of people to help solve a problem.

Digital Divide

Unequal access to computers and the Internet based on factors like poverty, racism, age, and isolation.

Encryption

The process of transforming original information into a scrambled format to obscure its meaning.

Symmetric Encryption

Any technique where the same key is used to both encrypt and decrypt data.

Asymmetric Encryption

Also known as public key encryption; uses different keys for encryption and decryption.

SSL/TLS

Secure Sockets Layer/Transport Layer Security; the standard for cryptographically secured information transfer on the Internet.

Certificate Authorities

Organizations that issue digital certificates to verify the ownership of encryption keys.

MFA

Multi-factor authentication; requires two or more verification factors (something you know, something you have, or something you are).

Decidable Problem

A problem for which an algorithm exists that will always terminate with a correct answer for any input.

Undecidable Problem

A problem for which no algorithm can determine the answer for all possible inputs, such as the Halting Problem.

Exponential Efficiency

Represented by $10^n$ permutations relative to the number of digits.

Heuristic

A problem-solving shortcut that is not always perfect but is good enough when a full analysis takes too long.

Lossless Compression

Reduces file size without losing information, allowing the original data to be perfectly reconstructed.

Lossy Compression

Reduces file size by discarding less important information, which affects file quality.

Run Length Encoding (RLE)

A lossless compression method where redundant sequences are stored as a single data value and a count of repetitions.

Analog Data

A continuous stream of varying data.

Digital Data

Finite data in a binary representation used by computers.

Sampling

The process of converting analog data to digital by recording data at regular time intervals.

Overflow Error

An error that occurs when attempting to represent a number that is too large for the fixed number of bits.

Round-off Error

An error that occurs when attempting to represent a number that is too precise, requiring the value to be rounded.

Sequential Computing

A model where programs run in order, one command at a time.

Parallel Computing

A model where programs are broken into small pieces and some are run simultaneously.

Distributed Computing

A model where programs are run by multiple devices.

Speedup

The sequential completion time divided by the parallel completion time.

Simulation

An abstraction of infinitely complex natural phenomena that removes unnecessary or difficult details.

Iterative Development

A process of continuous refinement and revision based on feedback, testing, or reflection.

Modular Development

Breaking a program into smaller pieces and ensuring each works before adding it to the whole.

Program Documentation

A description of how something in a program works, most commonly in the form of comments.

Identify

In the CSP course, to provide a name for a specific topic without elaboration or explanation.

Demonstrate

In the CSP course, to provide sufficient evidence for an answer or point being made.

Describe

In the CSP course, to provide the relevant features or characteristics of what the program code represents.