AP Comp Sci Principles

Binary

a way of representing information using only two options

Bit

a contraction of “Binary Digit”; the single unit of information in a computer, typically represented as a 0 or 1

Image

a type of data used for graphics or pictures.

Metadata

is data that describes other data. For example, a digital image may include metadata that describe the size of the image, number of colors, or resolution.

pixel

short for "picture element", the fundamental unit of a digital image, typically a tiny square or dot that contains a single point of color of a larger image.

Analog Data

data with values that change continuously, or smoothly, over time. Some examples of analog data include music, colors of a painting, or position of a sprinter during a race.

Digital Data

data that changes discreetly through a finite set of possible values

Sampling

a process for creating a digital representation of analog data by measuring the analog data at regular intervals called samples.

Lossless Compression

a process for reducing the number of bits needed to represent something without losing any information. This process is reversible.

Heuristic

a problem solving approach (algorithm) to find a satisfactory solution where finding an optimal or exact solution is impractical or impossible.

Lossy Compression:

a process for reducing the number of bits needed to represent something in which some information is lost or thrown away. This process is not reversible

Text

should use lossless / uncompressed because it already has a small file size and it’s important to be able to reconstruct the original message for communication purposes.

Video

should use lossy compression because it usually has a large file size which we need to reduce so we don’t use up all our data

Image & Audio

can have various answers, but what’s most important is how the answer is justified. Note that lossy compression is best when you want to save data or transmit quickly, and lossless when it’s important to perfectly recreate the original file.

Open Source

programs that are made freely available and may be redistributed and modified.

Open Access

online research output free of restrictions to access and use

Net Neutrality

is a raging legal debate about the principle that Internet service providers should enable access to all content and applications regardless of the source, and without favoring or blocking particular products or websites.

Internet Censorship

is the attempt to control or suppress what can be accessed, published, or viewed on the Internet by certain people. This can be used to protect people (i.e. to not allow access to child pornography) but can also be used to limit free speech.

Computing Device

a machine that can run a program, including computers, tablets, servers, routers, and smart sensors

Computer System

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

Computing Network

a group of interconnected computing devices capable of sending or receiving data.

Path

the series of connections between computing devices on a network starting with a sender and ending with a receiver.

Bandwidth

the maximum amount of data that can be sent in a fixed amount of time, usually measured in bits per second.

Protocol

An agreed-upon set of rules that specify the behavior of some system

IP Address

The unique number assigned to each device on the Internet.

Internet Protocol (IP)

a protocol for sending data across the Internet that assigns unique numbers (IP addresses) to each connected device

Packet

A chunk of data sent over a network. Larger messages are divided into packets that may arrive at the destination in order, out-of-order, or not at all.

Packet Metadata

Data added to packets to help route them through the network and reassemble the original message.

Transmission Control Protocol (TCP)

A protocol for sending packets that does error-checking to ensure all packets are received and properly ordered

User Datagram Protocol (UDP)

A protocol for sending packets quickly with minimal error-checking and no resending of dropped packets

HTTP - (HyperText Transfer Protocol)

A call-and-response protocol for client/server relationship, where a client requests a web page or other content (image, sound, video, etc.) from a server. The server looks for it and sends it back.

User Interface

the inputs and outputs that allow a user to interact with a piece of software. User interfaces can include a variety of forms such as buttons, menus, images, text, and graphics

Input

data that are sent to a computer for processing by a program. Can come in a variety of forms, such as tactile interaction, audio, visuals, or text.

Output

any data that are sent from a program to a device. Can come in a variety of forms, such as tactile interaction, audio, visuals, or text.

Program Statement

a command or instruction. Sometimes also referred to as a code statement.

Program

a collection of program statements. Programs run (or “execute”) one command at a time.

Sequential Programming

program statements run in order, from top to bottom.

Event Driven Programming:

some program statements run when triggered by an event, like a mouse click or a key press

Documentation

a written description of how a command or piece of code works or was developed.

Comment

form of program documentation written into the program to be read by people and which do not affect how a program runs

Expression

a combination of operators and values that evaluates to a single value

Variable

holds one value at a time

Assignment Operator

allows a program to change the value represented by a variable

myVar

creates a new variable

variable

a reference to a value or expression that can be used repeatedly throughout a program.

OverFlow Error

Error from attempting to represent a number that is too large.

Round-off Error

Error from attempting to represent a number that is too precise. The value is rounded.