FreeBSD is a free Unix-like operating system descended from AT&T UNIX via BSD UNIX.  Although for legal reasons FreeBSD cannot be called "UNIX", as the direct descendant of BSD UNIX (many of whose original developers became FreeBSD developers), FreeBSD's internals and system APIs are UNIX-compliant. Thanks to its permissive licensing terms, much of FreeBSD’s code base has become an integral part of other operating systems such as OS X that have subsequently been certified as UNIX-compliant and have formally received UNIX branding.  With the exception of the proprietary OS X, FreeBSD is the most widely used BSD-derived operating system in terms of number of installed computers, and is the most widely used freely licensed, open-source BSD distribution, accounting for more than three-quarters of all installed systems running free, open-source BSD derivatives.

FreeBSD is a complete operating system. The kernel, device drivers, and all of the userland utilities, such as the shell, are held in the same source code revision tracking tree.  (This is in contrast to Linux distributions, for which the kernel, userland utilities, and applications are developed separately, and then packaged together in various ways by others.)  Third-party application software may be installed using various software installation systems, the two most common being source installation and package installation, both of which use the FreeBSD Ports system.

Marshall Kirk McKusick (born January 19, 1954 in Wilmington, Delaware) is a computer scientist, known for his extensive work on BSD, from the 1980s to FreeBSD in the present day. He was president of the USENIX Association from 1990 to 1992 and again from 2002 to 2004, and still serves on the board. He is also on the editorial board of ACM Queue Magazine. He is known to friends and colleagues as "Kirk".

McKusick received his B.S. in electrical engineering from Cornell University, and 2 M.S. degrees (in 1979 and 1980 respectively) and a Ph.D. in computer science from the University of California, Berkeley in 1984. [1]

He lives in California with Eric Allman, his domestic partner since graduate school. McKusick is an avid wine collector and the temperature and vital statistics of his house and wine cellar are available on the web from his homepage.

McKusick started with BSD by virtue of the fact that he shared an office at Berkeley with Bill Joy, who in essence spearheaded the beginnings of the BSD system.

Marshall Kenneth Kirk (December 8, 1957 – approx. July 28, 2005) was a New England Historic Genealogical Society librarian, and a noted writer and a researcher in neuropsychiatry. He is, however, best known as one of the co-authors of "After the Ball" a strategy for the LGBT movement in the 1990s.

Marshall was born in Norway, Maine, the third child of Roger Marchant and Kathleen Marie (Murphy) Kirk, and was raised in Mechanic Falls. Marshall had two brothers, Roger and Douglas, and a sister, Kathy. Growing up Kirk took interest in weather; his brothers report that at age 10 his fellow townsmen in Mechanic Falls, Maine, preferred his forecasts to anything on television. He was valedictorian of his high school class and graduated magna cum laude from Harvard University in 1980, majoring in psychology, and writing his honors thesis on the testing of gifted children.

His interest in his own colonial New England forebears broadened into the study of pre-American ancestry. He became internationally known as one of the three or four major American authorities on medieval and ancient genealogy (Greece, Rome, Egypt, Persia, Armenia, the Merovingians and Carolingians).