Key Concepts in Computing and Data Representation

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.

Byte

8 bits.

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.

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 discretely 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.

Lossy Compression

A process for reducing the number of bits needed to represent something in which ....

Computing Device

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

Computing 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 ....

World Wide Web

A system of linked pages, programs, and files.

Digital Divide

Differing access to computing devices and the Internet, based on socioeconomic, geographic, or demographic characteristics.

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.

Pair Programming

A collaborative programming style in which two programmers switch between the roles of writing code and tracking or planning high level progress.

Debugging

Finding and fixing problems in an algorithm or program.

Development process

The steps or phases used to create a piece of software. Typical phases include investigating, designing, prototyping, and testing.

Event

Associated with an action and supplies input data to a program. Can be generated when a key is pressed, a mouse is clicked, a program is started, or by any other defined action that affects the flow of execution.

Expression

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

Assignment Operator

Allows a program to change the value represented by a variable.

Variable

A named reference to a value that can be used repeatedly throughout a program.

String

An ordered sequence of characters.

Boolean Value

A data type that is either true or false.

Comparison Operators

<, >, <=, >=, ==, != indicate a Boolean expression.

Logical operator

NOT, AND, and OR, which evaluate to a Boolean value.

Conditional Statement

Affect the sequential flow of control by executing different statements based on the value of a Boolean expression.

Function

A named group of programming instructions. Also referred to as a 'procedure'.

Function Call

A command that executes the code within a function.

List

an ordered collection of elements.

Element

an individual value in a list that is assigned a unique index.

Index

a common method for referencing the elements in a list or string using numbers.

Iteration

a repetitive portion of an algorithm which repeats a specified number of times or until a given condition is met.

Infinite loop

occurs when the ending condition will never evaluate to true.

Traversal

the process of accessing each item in a list one at a time.

Data abstraction

manage complexity in programs by giving a collection of data a name without referencing the specific details of the representation.

Problem

a general description of a task that can (or cannot) be solved with an algorithm.

Algorithm

a finite set of instructions that accomplish a task.

Sequencing

putting steps in an order.

Selection

deciding which steps to do next.

Efficiency

a measure of how many steps are needed to complete an algorithm.

Linear Search

a search algorithm which checks each element of a list, in order, until the desired value is found.

Sequential Computing

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

Parallel Computing

a model in which programs are broken into small pieces, some of which are run simultaneously.

Distributed Computing

a model in which programs are run by multiple devices.

Speedup

the time used to complete a task sequentially divided by the time to complete a task in parallel.

Parameter

a variable in a function definition. Used as a placeholder for values that will be passed through the function.

Library

a group of functions (procedures) that may be used in creating new programs.

API

Application Program Interface - specifications for how functions in a library behave and can be used.

Citizen Science

scientific research conducted in whole or part by distributed individuals, many of whom may not be scientists, who contribute relevant data to research using their own computing devices.

Cleaning Data

a process that makes the data uniform without changing its meaning (e.g., replacing all equivalent abbreviations, spellings, and capitalizations with the same word).

Correlation

a relationship between two pieces of data, typically referring to the amount that one varies in relation to the other.

Crowdsourcing

the practice of obtaining input or information from a large number of people via the Internet.

Information

the collection of facts and patterns extracted from data.

Data bias

data that does not accurately reflect the full population or phenomenon being studied.

Data filtering

choosing a smaller subset of a data set to use for analysis, for example by eliminating / keeping only certain rows in a table.

Computing Innovation

includes a program as an integral part of its function. Can be physical (e.g. self-driving car), non-physical computing software (e.g. picture editing software), or non-physical computing concepts (e.g., e-commerce).

Personally Identifiable Information (PII)

information about an individual that identifies, links, relates, or describes them.

Phishing

a technique that attempts to trick a user into providing personal information. That personal information can then be used to access sensitive online resources, such as bank accounts and emails.

Keylogging

the use of a program to record every keystroke made by a computer user in order to gain fraudulent access to passwords and other confidential information.

Malware

software intended to damage a computing system or to take partial control over its operation.

Rogue Access Point

a wireless access point that gives unauthorized access to secure networks.

Encryption

a process of encoding messages to keep them secret, so only 'authorized' parties can read it.

Decryption

a process that reverses encryption, taking a secret message and reproducing the original plain text.

Symmetric Key Encryption

involves one key for both encryption and decryption.

Public Key Encryption

pairs a public key for encryption and a private key for decryption. The sender does not need the receiver's private key to encrypt a message, but the receiver's private key is required to decrypt the message.

Multi-factor Authentication

a system that requires at least two steps to unlock protected information; each step adds a new layer of security that must be broken to gain unauthorized access.