The Linux Kernel is the core component of the Linux operating system—a free, open-source, monolithic, Unix-like system kernel initiated by Linus Torvalds in 1991 and since evolved into a foundational technology powering everything from servers and supercomputers to smartphones and embedded devices. There are various text files in the Documentation/ subdirectory, several of them using the reStructuredText markup notation. Extensive filesystem compatibility (ext4, Btrfs, FUSE, XFS, etc.) Broad hardware architecture support (x86, ARM, mainframe, embedded, etc.)