Linux is the kernel of operating systems that look like and perform as well or better than the famous operating system from AT&T Bell Labs. Linus Torvalds and a loosely knit team of volunteer hackers from across the Internet wrote (and still are writing) Linux from scratch. It has all of the features of a modern, fully fledged operating system: true multitasking, threads, virtual memory, shared libraries, demand loading, shared, copy-on-write executables, proper memory management, loadable
device driver modules, video frame buffering, and TCP/IP networking.
Most people, however, refer to the operating system kernel, system software, and application software, collectively, as "Linux," and that convention is used in this FAQ as well.
Linux was written originally for 386/486/586-based PC's, using the hardware facilities of the 80386 processor family to implement its features. There are now many ports to other hardware platforms. ("Ports to Other Processors.")
There are also Linux distributions specifically for mobile and handheld platforms. An API specification and developers kit for the Crusoe Smart Microprocessor developed by Transmeta Corporation are at http://www.transmeta.com/. Information on the Linux distribution for the Compaq iPAQ is at http://www.handhelds.org/
Refer also to the Linux INFO-SHEET for more details as well as the answers to "Where Is the Documentation?", "What Hardware Is Supported?", and "Ports to Other Processors.", below. A list updated weekly is at: http://lwn.net/ Archive of many of the distributions are on line at: ftp://ftp.tux.org/ and http://planetmirror.com/pub/linux.
The Linux kernel is distributed under the GNU General Public License. ("What Is Linux's Open-Source License?")
There is a historical archive of all versions of the Linux kernel at http://ps.cus.umist.ac.uk/~rhw/kernel.versions.html.