Linux is an open source operating system initially developed for Intel processors but now available on other platforms. The Linux kernel was created by Linus Torvalds and forms the core of any Linux distribution. Distributions package the kernel with other software and come in different categories for embedded systems, desktops, and servers. Common distributions include Ubuntu, Fedora, and CentOS. The command line interface provides power and flexibility, while the graphical user interface offers accessibility through desktop environments like GNOME.