When you log in to a Linux system for the first time, before doing any work, it is always a good idea to check what version of Linux is running on the machine. Some of the most popular Linux distributions are Debian, Red Hat, Ubuntu, Arch Linux, Fedora, CentOS, Kali Linux, OpenSUSE, Linux Mint, etc. Usually, Linux distributions include desktop environments, package management system, and a set of preinstalled applications. A Linux distribution is an operating system made from a Linux kernel, GNU tools and libraries, and software collections. Strictly speaking, Linux is a kernel, the core component of the operating system that, simply put, acts just like a bridge between the software applications and the hardware. When people refer to Linux, they are usually referring to a Linux distribution.