application (app)

A program designed for a specific user task, such as a browser, word processor, game, or utility.

asymmetric encryption

Encryption that uses a matched public key and private key pair.

authentication

The process of proving identity, usually with a username/password or another credential.

bare metal

A system where an operating system is installed directly on physical server hardware.

Beowulf clustering

A Linux clustering method where multiple computers work together on parallel computing tasks.

build automation

Software/processes that automatically create containers, virtual machines, or deployable builds with the correct settings.

certificate

A public key that has been digitally signed by a trusted Certification Authority.

Certification Authority (CA)

A trusted third party that digitally signs public keys to create certificates.

closed source software

Software whose source code is not made available to users.

cloud delivery model

A method for providing cloud resources, such as IaaS, PaaS, or SaaS.

cloud provider

An organization that hosts cloud servers and offers cloud resources.

clustering

Combining multiple computers so they function together as one larger system.

code repository

A server or service where developers store, track, review, and share source code.

Common Gateway Interface (CGI)

A method that lets web servers run programs to process requests and generate dynamic content.

container

A lightweight environment that contains an app and needed files but shares the host operating system kernel.

container runtime

Software that runs and manages containers, such as Docker, Podman, or LXC.

continuous deployment (CD)

A workflow that automatically tests and deploys new app versions to production after approval.

continuous integration (CI)

A process where new code is submitted, reviewed, tested, and integrated into a shared code base.

copyleft license

An open source license that requires derivative works to keep the same freedoms; GPL is an example.

cracker

A person who illegally uses computers for personal gain or to cause damage.

daemon

A Linux background service that provides system or network functionality.

database

An organized collection of related data, often stored in tables.

database management system (DBMS)

Software that creates, manages, stores, and retrieves data in databases.

desktop environment

A GUI environment that controls the look and feel of the Linux desktop, such as GNOME or KDE.

development kernel

A kernel version that is still being tested and may be unstable.

device driver

Software that tells the operating system how to communicate with a specific hardware device.

DevOps

People or practices that combine development and operations to support app deployment workflows.

digital signature

Data encrypted with a private key to prove the sender or verify authenticity.

distribution (distro)

A packaged version of Linux containing the kernel, libraries, utilities, and applications.

distribution kernel

A Linux kernel modified by a distribution for fixes, optimizations, or long-term support.

Domain Name Space (DNS)

A service/system that maps FQDN names to IP addresses.

Dynamic Host Configuration Protocol (DHCP)

A protocol that automatically gives computers IP addresses and related network settings.

File Transfer Protocol (FTP)

A protocol used to transfer files over a network or the Internet.

firewall

A system that controls network traffic based on rules to protect a network.

flavor

A variety or version of an operating system, especially UNIX.

forum

An online discussion area where people post questions, answers, and information.

Free Software Foundation (FSF)

An organization founded by Richard Stallman to promote free software.

freeware

Closed source software distributed free of charge.

fully qualified domain name (FQDN)

A full, human-readable network name for a host, such as www.linux.org.

GNU General Public License (GPL)

A copyleft license requiring source code and modifications to remain freely available.

GNU Network Object Model Environment (GNOME)

A popular Linux desktop environment.

GNU Project

A project started in 1984 to create a free operating system and free software tools.

graphical user interface (GUI)

A user interface with windows, menus, icons, and mouse/keyboard interaction.

hacker

A person who experiments to expand computing knowledge and improve software or systems.

hardware

The physical electrical components of a computer, such as CPU, RAM, drives, and network cards.

hybrid cloud

A cloud setup that uses both public and private cloud resources together.

Hypertext Transfer Protocol (HTTP)

A protocol used by web browsers and web servers to transfer webpages and web content.

Infrastructure as a Service (IaaS)

A cloud model where the provider supplies infrastructure and the subscriber manages virtual machines and software.

Internet of Things (IoT)

Internet-connected devices such as sensors, smart locks, smart speakers, and embedded systems.

Internet Protocol (IP) address

A numeric address that uniquely identifies a computer or device on a network.

Internet Service Provider (ISP)

A company that provides Internet access to users or organizations.

K Desktop Environment (KDE)

A popular Linux desktop environment with a Windows-like feel.

Kerberos

An authentication protocol that uses tickets to prove identity across network services.

kernel

The core of an operating system that manages hardware, memory, processes, and device drivers.

key

A random or secret value used by an encryption algorithm to encrypt or decrypt data.

Linus Torvalds

The Finnish student who created the Linux kernel in 1991.

Linux

An open source UNIX-like operating system based on the Linux kernel and supporting software.

Linux User Group (LUG)

A local or online group of Linux users who share knowledge and help each other.

load balancing

Distributing requests across multiple servers to improve speed and fault tolerance.

Mail Transfer Agent (MTA)

Email server software that transfers email messages between systems.

major number

The first number in a Linux kernel version; it identifies the major kernel version.

Message Passing Interface (MPI)

A framework that lets computers in a cluster exchange messages for parallel processing.

minor number

The second number in a Linux kernel version; it identifies the minor revision or feature level.

Multiplexed Information and Computing Service (MULTICS)

A 1960s time-sharing operating system project that influenced UNIX.

Network Address Translation (NAT)

A method that tracks and translates network addresses so internal systems can access outside networks.

Network Time Protocol (NTP)

A protocol used to synchronize system time across computers.

open source software (OSS)

Software whose source code is available to read, modify, and redistribute.

operating system

Software that controls hardware, runs applications, and provides services and a user interface.

orchestration

Automated coordination and management of containers, virtual machines, services, or deployment steps.

package manager

Software that installs, updates, tracks, and removes software packages.

permissive license

An open source license with fewer restrictions than copyleft licenses, such as MIT, BSD, or Apache.

Platform as a Service (PaaS)

A cloud model where the provider supplies the platform and runtime, and the subscriber manages containers/apps.

private cloud

Cloud servers used only by the organization that owns or controls them.

private key

The secret key in asymmetric encryption; it is never shared.

process

A running program that is actively performing a task.

production kernel

A stable, tested Linux kernel version intended for regular use.

program

A file containing instructions that can be executed by a computer.

programming language

A structured language used to write source code, such as C, Python, or JavaScript.

proxy server

A server that requests Internet resources on behalf of internal client computers.

public cloud

Cloud servers on the Internet that can be rented or used by other organizations or users.

public key

The shareable key in asymmetric encryption used to encrypt data or verify digital signatures.

Public Key Infrastructure (PKI)

A system of CAs, certificates, keys, and policies used to manage trusted encryption identities.

revision number

The third number in a Linux kernel version; it identifies smaller fixes or releases.

router

A device or computer that forwards traffic between networks.

sandbox

An isolated software environment used to improve security and reliability.

scalability

The ability of a system to handle more work as resources are added.

Secure Sockets Layer (SSL)

An older encryption technology used to secure network communication; largely replaced by TLS.

security appliance

A specialized device or server that provides network security services.

server

A computer that hosts services or resources for other systems across a network.

service

A background program that provides system or network functionality.

shareware

Closed source software that is free at first but requires payment later or for more features.

software

Programs or instructions that tell computer hardware what to do.

Software as a Service (SaaS)

A cloud model where the provider manages most infrastructure and delivers an app/service to users.

source code

Human-readable instructions written by developers before being compiled or interpreted.

symmetric encryption

Encryption that uses the same key to encrypt and decrypt data.

tarball

A compressed archive of files often used to distribute Linux software or source code.

total cost of ownership (TCO)

The overall cost of using a system, including software, hardware, support, maintenance, training, and upgrades.

Transport Layer Security (TLS)

The modern encryption protocol used to secure network communication, including HTTPS.

UNIX

A portable, multiuser operating system created at AT&T Bell Labs in 1969.

user

A person who uses a computer or system.

user interface

A program or environment that accepts user input and shows results.

virtual machine

A software-based computer that runs its own operating system on a hypervisor.

virtualization software (hypervisor)

Software that allows multiple virtual machines to run on the same physical hardware.

web app

A software program on a web/cloud server accessed through a browser, mobile app, program, or device.

web app framework

A collection of software modules that helps developers build web apps more easily.

World Wide Web (WWW)

The worldwide collection of web servers and web content accessed over the Internet.

X Windows

The core graphical windowing system historically used by Linux and UNIX GUIs.