Dictionary

This page lists terms and abbreviations used across ITLearn. If you meet a word or acronym you do not understand, check here first.

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Computing Fundamentals

API (Application Programming Interface) - A defined way for two pieces of software to communicate.
CLI (Command Line Interface) - A text-based way to control a computer, as opposed to a GUI.
CPU (Central Processing Unit) - The processor. It runs instructions and performs the computer’s calculations.
GUI (Graphical User Interface) - A visual, point-and-click way to control a computer.
OS (Operating System) - The software that manages hardware and runs other programs. Examples: Linux, Windows, macOS.
RAM (Random Access Memory) - Fast, temporary memory used while programs run.
VM (Virtual Machine) - A software copy of a computer that runs like physical hardware.

DHCP (Dynamic Host Configuration Protocol) - Assigns IP addresses to devices on a network automatically.
DNS (Domain Name System) - Converts domain names into IP addresses.
IP (Internet Protocol) - The addressing system that lets devices find and send data to each other.
LAN (Local Area Network) - A network limited to a small area, such as a home or office.
NAT (Network Address Translation) - Lets multiple devices share one public IP address.
OSI Model (Open Systems Interconnection Model) - A seven-layer model that describes how network communication works.
TCP/IP (Transmission Control Protocol/Internet Protocol) - The core protocol suite the internet runs on.
VLAN (Virtual Local Area Network) - A separate network segment created inside a physical network.
VPN (Virtual Private Network) - An encrypted tunnel that extends a private network across a public one.
WAN (Wide Area Network) - A network that covers a large geographic area and connects multiple LANs.

CVE (Common Vulnerabilities and Exposures) - A public record of a known security vulnerability.
IAM (Identity and Access Management) - Systems and processes that control who can access what.
MFA (Multi-Factor Authentication) - A login that requires two or more different types of authentication factor, such as a password plus a one-time code.
PKI (Public Key Infrastructure) - The certificates and keys used to secure communications and verify identity.
RBAC (Role-Based Access Control) - Grants permissions based on a user’s role, not the individual user.
SIEM (Security Information and Event Management) - Tooling that collects and analyses security logs across an environment.
SOC (Security Operations Centre) - The team that monitors and responds to security threats.
SSH (Secure Shell) - An encrypted protocol used to access and manage systems remotely.
TLS (Transport Layer Security) - The protocol used to encrypt data in transit, such as HTTPS traffic. SSL (Secure Sockets Layer) is its obsolete predecessor.

CI/CD (Continuous Integration/Continuous Deployment) - Automated pipelines that test and release code changes.
IaC (Infrastructure as Code) - Managing infrastructure through version-controlled configuration files, not manual setup.
SLA (Service Level Agreement) - A formal commitment to a defined standard of service, such as uptime.
SLO (Service Level Objective) - An internal target used to measure and manage service reliability.
SRE (Site Reliability Engineering) - A discipline that applies software engineering practices to operations and reliability.

CapEx (Capital Expenditure) - Upfront spending on infrastructure or assets. Compare with OpEx, ongoing operating costs.
ITIL (Information Technology Infrastructure Library) - A widely used framework of best practices for IT service management.
ITSM (IT Service Management) - The processes used to design, deliver, and support IT services.

Self-Hosting - Running your own services on infrastructure you control, instead of relying on a third-party provider.
Vendor Lock-in - A situation where switching away from a provider’s product or service becomes costly or impractical.

This glossary grows alongside the course content. Each definition stays short by design. Each path covers its own terms in full depth.