Source code for the entire system means you have the greatest degree of control over your environment. Extensive online documentation . In addition to the fine work provided by CSRG, the FreeBSD Project has put in many thousands of hours in fine tuning the system for maximum performance and reliability in real-life load situations. The applications to which FreeBSD can be put are truly limited only by your own imagination. FreeBSD also benefits significantly from the literally thousands of high quality applications developed by research centers and universities around the world, often available at little to no cost.
Commercial applications are also available and appearing in greater numbers every day.
Because the source code for FreeBSD itself is generally available, the system can also be customized to an almost unheard of degree for special applications or projects, and in ways not generally possible with operating systems from most major commercial vendors. With FreeBSD, you can easily start out small with an inexpensive 386 class PC and upgrade all the way up to a quad-processor Xeon with RAID storage as your enterprise grows. There is no better way of learning about operating systems, computer architecture and networking than the hands on, under the hood experience that FreeBSD can provide. With source code for the entire system available, FreeBSD is an excellent platform for research in operating systems as well as other branches of computer science. FreeBSD's freely available nature also makes it possible for remote groups to collaborate on ideas or shared development without having to worry about special licensing agreements or limitations on what may be discussed in open forums.