Linux is aUnix-like and mostly POSIX-compliant computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released on 5 October 1991 by Linus Torvalds. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux when referring to the operating system as a whole, to emphasize the importance of GNU software, especially the GNU Compiler Collection (GCC), in the creation of what they consider a free operating system.
Development of the Linux kernel began in 1991 with the aim of creating a free and open source alternative to Minix, a proprietary Unix-like operating system. Linus Torvalds, the principal author of the Linux kernel, launched the development of the Linux kernel on 5 October 1991. On 17 August 1993, he released the first version of the Linux kernel, version 0.01.
Since then, Linux has been adopted as the kernel for many operating systems, most notably Debian, Ubuntu, Mint, Fedora, Red Hat Enterprise Linux, SUSE Linux Enterprise Server, Gentoo Linux, Arch Linux, and Android. It is also used in many consumer devices such as routers, set-top boxes, digital video recorders, and video game consoles.
Linux is a monolithic kernel, meaning that all the operating system's components are integrated into a single executable file, the kernel. The advantage of this design is that it improves system performance and stability by reducing the latency between user requests and kernel responses.
Linux also supports a wide range of hardware platforms, from personal computers to supercomputers. This is possible because the kernel can be configured to run on any hardware platform, and because of the availability of a large number of open source drivers.
There are hundreds of Linux distributions, each with a different focus. Some distributions, such as Debian and Ubuntu, are designed for general-purpose use, while others, such as Fedora and Red Hat Enterprise Linux, are designed for specific use cases, such as server administration or software development.
A desktop environment is a collection of software that provides a graphical user interface (GUI) and a set of applications for working with the operating system. The most popular desktop environments for Linux are GNOME, KDE, and Xfce.
Linux systems come with a wide variety of software installed by default, including a web browser, a office suite, and a set of tools for software development. In addition, there are thousands of applications available for installation from online repositories.
Linux is a text-based operating system, which means that users interact with the system using text commands. The command line is a powerful tool for managing a Linux system, and it is often necessary to use the command line to perform tasks that cannot be accomplished using the graphical user interface.
Linux uses a hierarchical file system, which means that files are organized into directories, and directories can contain other directories. The file system is organized into a tree, with the root directory (/) at the top.
A user is an individual who uses a Linux system. Each user has a unique user ID (UID) and is a member of one or more groups. Groups are used to organize users and to control access to resources, such as files and directories.
A process is a running instance of a program. Every process has a unique process ID (PID) and is associated with a particular user and group. Processes are created and terminated by the operating system.
A service is a process that is started automatically when the system boots and that runs in the background. Services provide functionality that is not directly related to the user interface, such as network file sharing or email.
Linux systems are designed to be secure, and they include a variety of tools for managing security. For example, the sudo command can be used to give users temporary access to root privileges, and the iptables command can be used to configure the firewall.