Jordan Hubbard, Apple Computer says, not confined to operating systems, the BSD world also contains a wide selection of libraries, tools, and generally useful code that is distributed under the very liberal BSD license. This license essentially allows code to be used for almost any purpose, closed or open source, and without “encumbering” licensing effects for third-party code that uses it. The original BSD distributions spawned a number of independent projects such as FreeBSD, NetBSD, and OpenBSD, all of which continue to do innovative work that is released under the same BSD license. This has made BSD software a popular choice for commercial software and hardware vendors, who are thus free to create closed source variants of their products without undue restrictions. Read more.