AI105 Cyberspace writ

Input device

A hardware device that sends data or commands into a computer, such as a keyboard, mouse, microphone, or camera.

Output device

A hardware device that presents information from a computer, such as a monitor, speaker, or printer.

RAM (Random Access Memory)

Fast, temporary memory that holds the programs and data currently being used; its contents disappear when power is turned off.

Hard drive

A nonvolatile storage device that keeps the operating system, applications, and files after the computer is turned off.

Peripheral device

A device connected to a computer that provides additional input, output, storage, or communication capabilities.

CPU (Central Processing Unit)

The computer component that executes instructions, performs calculations, and coordinates the other components.

Binary

A number system using only 0 and 1 that computers use to represent and process data.

Bit

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

Byte

A group of eight bits commonly used to represent a character or another small unit of data.

File extension

The ending of a filename, such as .docx or .jpg, that helps the operating system determine which application should open it and how to interpret its data.

Operating system (OS)

System software that manages a computer’s hardware, files, applications, and user interactions.

Artificial intelligence (AI)

The broad field of creating computer systems capable of performing tasks associated with human intelligence.

Machine learning (ML)

A branch of AI in which a system learns patterns from data instead of being explicitly programmed for every situation.

Generative AI (Gen AI)

AI designed to create new content such as text, images, audio, video, or computer code.

Large language model (LLM)

A machine-learning model trained on large amounts of text to recognize patterns in language and generate responses.

Artificial narrow intelligence

AI designed to perform a specific task or limited group of tasks; nearly all current AI belongs to this category.

Artificial general intelligence (AGI)

A theoretical AI capable of learning and performing a wide variety of intellectual tasks at approximately human level.

Artificial superintelligence (ASI)

A hypothetical AI that would exceed human intelligence across most or all intellectual areas.

Network

A group of connected devices that communicate and share data, resources, or services.

Ethernet

A wired networking technology that usually provides a fast, stable connection through cables.

Wi-Fi

A wireless technology that uses radio waves to connect devices to a local network.

Bluetooth

A short-range wireless technology commonly used to connect accessories such as headphones, keyboards, and smartwatches.

Cellular network

A wireless network that uses cell towers to provide mobile communication and Internet access over a large area.

Bandwidth

The amount of data a connection can transfer during a certain amount of time; commonly measured in Mbps or Gbps.

Latency

The delay between sending data and receiving a response; commonly measured in milliseconds.

Range

The maximum distance over which a wireless signal or network connection can operate reliably.

Packet

A small unit into which data are divided before being transmitted across a network.

Router

A network device that receives packets and directs them toward their intended destinations.

Absolute reference

A reference containing the complete location of a resource, such as a full URL; it does not depend on the current file’s location.

Relative reference

A reference that locates a resource in relation to the current webpage, file, or folder.

Internet

The global system of connected computer networks and infrastructure that allows devices to communicate.

World Wide Web

A collection of linked webpages and online resources accessed through web browsers using the Internet.

Domain Name System (DNS)

The service that translates human-readable domain names into numerical IP addresses that computers can use.

Domain name

The human-readable name used to identify an Internet location, such as example.com.

IP address

A numerical address that identifies a device or location on a network.

Uniform Resource Locator (URL)

The complete address used to locate a webpage, file, or other resource on the Web.

HTML (Hypertext Markup Language)

The language used to define the content and structure of a webpage.

CSS (Cascading Style Sheets)

The language used to control a webpage’s appearance and layout, including colors, fonts, and spacing.

JavaScript

A programming language used to add behavior and interactivity to webpages.

Surface Web

Publicly accessible webpages that standard search engines can discover and index.

Deep Web

Online content that standard search engines do not index, often because it requires authentication or is stored in a private database.

Dark Web

A deliberately hidden portion of the Deep Web that usually requires specialized software, such as Tor, to access.

Client

A device or application that requests a resource or service from a server.

Server

A computer or program that receives client requests and provides requested resources or services.

Client-server model

A system in which a client requests information or a service and a server processes the request and returns a response.

Cloud storage

A service that stores files on remote servers so they can be accessed or synchronized through a network.

Physical layer of cyberspace

The physical devices and infrastructure supporting cyberspace, such as computers, servers, routers, cables, satellites, and cell towers.

Logical layer of cyberspace

The software, protocols, addresses, and data that allow digital devices and networks to operate and communicate.

Cyber-persona layer of cyberspace

The digital identities representing people or organizations online, such as usernames, email accounts, and profiles.

Threat

Anything with the potential to cause harm to a system, network, or its information.

Threat actor

A person, group, or organization that carries out or supports a cyber threat.

Vulnerability

A weakness in hardware, software, procedures, or human behavior that a threat actor can exploit.

Exploit

A technique or piece of code used to take advantage of a vulnerability.

Alter

A threat goal involving unauthorized changes to information, which damages integrity.

Deny

A threat goal involving preventing authorized access to information or services, which damages availability.

Disclose

A threat goal involving revealing information to unauthorized people, which damages confidentiality.

Social engineering

The use of psychological manipulation to trick people into revealing information or performing an unsafe action.

Phishing

Fraudulent messages sent to potential victims to steal information, spread malware, or persuade them to visit a malicious website.

Spear phishing

A targeted and personalized form of phishing aimed at a specific person or organization.

Malware

Software intentionally designed to damage systems, disrupt operations, steal information, or gain unauthorized access.

Trojan

Malware disguised as legitimate or useful software that tricks a user into installing or running it.

Worm

Self-replicating malware that can spread across networks without attaching itself to another file.

Virus

Malicious code that attaches to another file or program and spreads when the infected host is executed or shared.

Ransomware

Malware that blocks access to a system or encrypts files and demands payment to restore access.

Spyware

Malware that secretly monitors activity and collects information from a device or user.

Adware

Software that displays unwanted advertisements and may also track user activity.

CIA Triad

A cybersecurity model consisting of confidentiality, integrity, and availability.

Confidentiality

The principle that information should be accessible only to authorized people; disclosure attacks confidentiality.

Integrity

The principle that information should remain accurate, complete, and protected from unauthorized changes; alteration attacks integrity.

Availability

The principle that authorized users should be able to access systems and information when needed; denial attacks availability.

Cryptography

The science of using mathematical techniques to protect information and communication.

Plaintext

Original, readable information before it is encrypted.

Ciphertext

Unreadable, encrypted information produced from plaintext.

Encryption

The process of converting plaintext into ciphertext using an algorithm and key.

Decryption

The process of converting ciphertext back into readable plaintext using the appropriate key.

Cryptographic key

A value used by a cryptographic algorithm to encrypt, decrypt, sign, or verify information.

Data at rest

Data stored on a device or storage system that are not currently moving across a network.

Data in transit

Data actively moving from one device or location to another across a network.

Symmetric cryptography

Encryption that uses the same shared secret key for encryption and decryption; it is fast but requires secure key sharing.

Asymmetric cryptography

Cryptography that uses a mathematically related public key and private key for encryption, decryption, and digital signatures.

Public key

The shareable key in asymmetric cryptography; it can encrypt information for the key owner or verify the owner’s digital signature.

Private key

The secret key in asymmetric cryptography; it can decrypt information encrypted with the corresponding public key or create digital signatures.

Digital signature

Cryptographic evidence created with a sender’s private key to verify identity and show that information has not been altered.

Authenticity

Assurance that a user, sender, device, or message is genuinely what it claims to be.

Nonrepudiation

Assurance that the creator or sender of information cannot credibly deny having signed or sent it.

Certificate authority (CA)

A trusted organization that verifies identities and issues digitally signed certificates.

Digital certificate

An electronic credential that connects an identity, such as a website, to a public key.

HTTPS

A secure version of HTTP that uses encryption and digital certificates to protect communication between a browser and website.

Data compression

The process of reducing the amount of storage space or bandwidth required for data.

Lossless compression

Compression that preserves all original data, allowing the file to be reconstructed exactly.

Lossy compression

Compression that permanently removes some data to create a smaller file, meaning the original cannot be reconstructed perfectly.

Controlled Unclassified Information (CUI)

Government information that is not classified but requires safeguarding or controlled dissemination under applicable laws, regulations, or policies.

Personally Identifiable Information (PII)

Information that can identify or trace a specific person by itself or when combined with other information.