Linux is a free open source computer operating system initially developed for Intel x86-based computers (x86 is a type of computer architecture that is based on CISC – Complex Instruction Set Computing). Linus Torvalds in 1991 started a project to write his own operating system kernel. He extended his project to construct an entire operating system with his kernel at the center. This soon became popular as the Linux kernel.
Linux is licensed using the General Public License (GPL) by GNU (a project of the Free Software Foundation (FSF) which promotes freely available software) which made it possible to build a worldwide community of developers. By combining the kernel with other system components, numerous other developers created several complete operating systems called Linux Distributions.
Choosing the right Linux Distribution is critical to the project. Therefore, it is important to understand the fundamental differences in several available Linux Distributions. All Linux Distributions can be categorized into two big categories – Commercial and Free. Oracle, Red Hat Enterprise Linux (RHEL), Suse Linux Enterprise Server are commercial Linux Distributions whereas CentOS, openSuse and Ubuntu are free Linux Distributions.
CentOS is a popular free alternative to RHEL. Ubuntu and Fedora are popular in the educational realm. Scientific Linux is favored by the scientific research community for its compatibility with scientific and mathematical software packages. Each distribution has their own set of applications, package management, configuration utilities etc., that are built around the kernel which is the core of the operating system. The current Linux kernel as well as the past Linux kernels can be found at the website: www.kernel.org.