linux final ultimate guide

Hardware

The tangible parts of a computer, such as the network boards, video card, hard disk drives, printers, and keyboards.

programs

An executable file on a filesystem. A program can be executed to create a process.

process

A program currently loaded into physical memory and running on the system.

Software

The programs stored on a storage device in a computer, which provide a certain function when executed.

applications (apps)

The software that runs on an operating system and provides specific functionality.

device driver

A piece of software the OS kernel uses to control and interact with a specific type of hardware.

graphical user interface (GUI)

An OS component that lets users interact with graphics/icons rather than command-line syntax.

operating system

The software used to control and directly interact with computer hardware components.

user

A person who uses a computer; also refers to file/directory owners in a Linux system.

user interface

The screen and controls that allow users to interact with the OS and applications.

services

A process that provides functionality to the local system or others on a network.

minor number

Identifies a specific hardware device within a given category (used by kernel device files).

Linux

A free, open-source OS based on UNIX, created by Linus Torvalds.

revision number

The third number in a kernel version that identifies the release version.

major number

The first number in a kernel version; also used to group related device drivers.

kernel

The core of the OS that interacts directly with hardware and provides low-level services.

production kernels

Stable Linux kernels used in production systems.

Source code

The instructions used to create a program, typically compiled into an executable.

Development kernels

Newly created Linux kernels still undergoing testing.

programming language

The syntax used to create source code.

open source software (OSS)

Software whose source code is freely available for modification and use.

closed source software

Software whose source code is not publicly available (e.g., Microsoft Windows).

permissive license

Open source license with minimal restrictions.

copyleft license

Open source license that requires changes to also be open source.

GNU General Public License (GPL)

A widely used copyleft license for free software.

Free Software Foundation (FSF)

An org founded by Richard Stallman to promote software freedom and open collaboration.

shareware

Software that is free to try but requires payment after a trial period.

freeware

Software that is permanently free to use.

forums

Online communities where users can post and answer technical questions.

total cost of ownership (TCO)

The full price of using a product, including training, maintenance, and support.

Internet of Things (IoT)

A network of small Internet-connected devices (like smart thermostats or fridges).

Linux User Groups (LUGs)

Communities of Linux users who help each other and promote Linux usage.

UNIX

The original multitasking, multiuser OS that inspired Linux.

flavor

A variant of UNIX or Linux, such as macOS, Ubuntu, etc.

MULTICS

A prototype time-sharing OS developed in the 1960s at AT&T Bell Labs.

hacker

A person who explores computing and software deeply (often ethically).

GNU Project

A free software initiative started by Richard Stallman.

cracker

A malicious user who exploits or damages systems.

distribution (distro)

A full Linux OS package including kernel, apps, utilities (e.g., Ubuntu, Fedora).

Linus Torvalds

Creator of the Linux kernel.

distribution kernels

Stable kernels with long-term support specific to Linux distributions.

desktop environments

Graphical shells like GNOME or KDE built on top of Linux.

GNOME

One of the two main desktop environments for Linux.

K Desktop Environment (KDE)

Another major Linux desktop environment.

X Windows

The GUI foundation in Linux that manages window graphics.

package manager

A tool to install, update, or remove Linux software (e.g., apt, yum).

bare metal

An OS running directly on hardware rather than in a VM.

sandbox

A restricted environment where apps run safely and isolated from the system.

tarball

A compressed archive file used to distribute software source code.

daemons

Background services that provide various system functions.

server

A computer that provides services to other computers on a network.

virtualization software

Software that runs multiple OSes on one computer.

container

A lightweight, isolated runtime environment for applications.

hypervisor

Software used to run multiple OSes on a single system.

virtual machine

An OS running inside virtualization software.

container runtime

The program that launches and manages containers.

TLS (Transport Layer Security)

A security protocol that encrypts network communication.

CGI (Common Gateway Interface)

A standard for web servers to interact with executable scripts.

SSL (Secure Sockets Layer)

An older encryption protocol replaced by TLS.

IP address

A unique number identifying a device on a network.

HTTP (Hypertext Transfer Protocol)

The protocol used for web pages and communication.

fully qualified domain names (FQDNs)

The complete name of a device in the DNS hierarchy.

NTP (Network Time Protocol)

A protocol used to sync system clocks across the Internet.

DNS (Domain Name System)

A system that translates domain names to IP addresses.

Mail Transfer Agents (MTAs)

Programs that send email between systems.

DHCP (Dynamic Host Configuration Protocol)

Automatically assigns IP addresses on a network.

database

A structured collection of information stored electronically.

FTP (File Transfer Protocol)

A protocol used to transfer files across the Internet.

key

A unique value used in encryption and security processes.

authentication

The process of confirming a user's identity.

DBMS (Database Management System)

A program that creates and manages databases.

Kerberos

An authentication protocol for computer networks.

symmetric encryption

Encryption where the same key is used to encrypt and decrypt.

digital signature

An encrypted hash used to verify data integrity and origin.

public key

The key used to encrypt data in asymmetric encryption.

private key

The key used to decrypt data in asymmetric encryption.

asymmetric encryption

Encryption that uses a public and a private key.

Certification Authority (CA)

A trusted entity that issues digital certificates.

clustering

A method to link multiple computers to work together.

certificate

A digital file used to verify the identity of a user or device.

PKI (Public Key Infrastructure)

A system of digital certificates and CAs used to secure communication.

scalability

The ability of a system to handle growing workloads.

Beowulf clustering

A method of linking Linux computers to form a supercomputer.

router

A device that forwards data between networks.

MPI (Message Passing Interface)

A protocol for communication in parallel computing.

firewall

A system that controls incoming and outgoing network traffic.

proxy server

A server that forwards requests to other servers.

load balancing

A technique that distributes workloads across servers.

NAT (Network Address Translation)

Allows multiple devices on a local network to share one public IP.

ISP (Internet Service Provider)

A company that provides access to the Internet.

firewalld

A Linux service used to manage firewall rules dynamically.

iptables

A powerful Linux command-line firewall tool.

masquerading

A form of NAT used to hide internal IP addresses.

forwarding

Enables the system to route traffic between interfaces.

stateful packet inspection

A firewall method that tracks the state of active connections.

zone

A predefined trust level used in Linux firewalld configurations.

interface

A network device like eth0 or wlan0 that connects a system to a network.

permanent rule

A firewalld rule that remains active after reboot.

runtime rule

A firewalld rule that exists only until reboot.

systemctl

A command-line tool to manage systemd services and units.