Linux distros (Linux distribution)
A Linux distribution -- often shortened to "Linux distro" -- is a version of the open source Linux operating system that is packaged with other components, such as an installation programs, management tools and additional software such as the KVM hypervisor.
Linux distributions, which are based on the Linux kernel, are often easier for users to deploy than the traditional open source version of Linux. This is because most distributions eliminate the need for users to manually compile a complete Linux operating system from source code, and because they are often supported by a specific vendor.
Linux distribution types
Hundreds of Linux distributions are available today, and each targets specific users or systems such as desktops, servers, mobile devices or embedded devices. Most distributions come ready to use, while others are packaged as source code that a user must compile during installation.
Some distributions, such as Fedora and Red Hat Enterprise Linux from Red Hat, openSUSE from SUSE, Ubuntu from Canonical, and Oracle Linux from Oracle, are commercial, while others, such as Debian and Slackware, are community-developed. Some commercial distributions, for example those from Red Hat and Oracle, charge users for services, such as support or custom development, although open source licensing prohibits charging for the open source software itself.
Linux distro packages
Generally, Linux distributions consist of what are called software packages. These packages contain specific files, applications or services. For example, a package could be a collection of fonts, web browsers or development environments. A single Linux distribution could contain thousands of software packages. In practical terms, however, Linux distros tend to minimize the number of components and modules to tailor the distro and shrink the operating system's total footprint -- especially if the distro will be deployed in a virtualized environment where many concurrent instances put compute resources at a premium.
A Linux distribution also includes a package management system, or packet manager, which is used to install, uninstall and manage software packages. These systems also allow for package searches, automatic software upgrades and verification that all package dependencies are fulfilled. Examples of package managers include Red Hat Package Manager, Yellowdog Updater, Modified and Advanced Packaging Tool.
Open source development
Linux is founded upon open source software development. Linux distributions emerged under the copyleft stipulations of the Free Software Foundation, which originated the GNU General Public License (GPL). Copyleft dictates that any software taken for free and altered must be consequently distributed for free. So if a developer uses Linux, or GNU components, to create a new version of Linux, the new version must be free. Commercial Linux vendors such as Red Hat typically generate revenue from services and tools rather than the Linux package itself.