What is Linux?
Linux is a clone of the operating system Unix, written from scratch by Linus Torvalds with assistance from a loosely-knit team of hackers across the Net. It aims towards POSIX and Single UNIX Specification compliance.
It has all the features you would expect in a modern fully-fledged Unix, including true multitasking, virtual memory, shared libraries, demand loading, shared copy-on-write executables, proper memory management, and multistack networking including IPv4 and IPv6.
Although originally developed first for 32-bit x86-based PCs (386 or higher), today Linux also runs on (at least) the Alpha AXP, Sun SPARC, Motorola 68000, PowerPC, ARM, Hitachi SuperH, IBM S/390, MIPS, HP PA-RISC, Intel IA-64, AMD x86-64, AXIS CRIS, Renesas M32R, Atmel AVR32, Renesas H8/300, NEC V850, Tensilica Xtensa, and Analog Devices Blackfin architectures; for many of these architectures in both 32- and 64-bit variants.
Linux is easily portable to most general-purpose 32- or 64-bit architectures as long as they have a paged memory management unit (PMMU) and a port of the GNU C compiler (gcc) (part of The GNU Compiler Collection, GCC). Linux has also been ported to a number of architectures without a PMMU, although functionality is then obviously somewhat limited. See the µClinux project for more info.
New to Linux?
If you're new to Linux, you don't want to download the kernel, which is just a component in a working Linux system. Instead, you want what is called a distribution of Linux, which is a complete Linux system. There are numerous distributions available for download on the Internet as well as for purchase from various vendors; some are general-purpose, and some are optimized for specific uses. We currently have mirrors of several distributions available at mirrors.kernel.org, as well as a small collection of special-purpose distributions at
http://www.kernel.org/pub/dist/.Note, however, that most distributions are very large (several gigabytes), so unless you have a fast Internet link you may want to save yourself some hassle and purchase a CD-ROM with a distribution; such CD-ROMs are available from a number of vendors.
The Linux Installation HOWTO has more information how to set up your first Linux system.
