Briefly, FreeBSD 2.X is a UN*X-like operating system based on U.C. Berkeley's 4.4BSD-lite release for the i386 platform. It is also based indirectly on William Jolitz's port of U.C. Berkeley's Net/2 to the i386, known as 386BSD, though very little of the 386BSD code remains. A fuller description of what FreeBSD is and how it can work for you may be found on the FreeBSD home page.
FreeBSD is used by companies, Internet Service Providers, researchers, computer professionals, students and home users all over the world in their work, education and recreation. See some of them in the FreeBSD Gallery.
For more detailed information on FreeBSD, please see the FreeBSD Handbook.