Berkeley Software Distribution (BSD) is one of the three major derivates of the Unix operating system from which many versions have been created such as OpenBSD, FreeBSD, NetBSD, Trusted BSD, and very early versions of Sun MicrosystemsSolaris. BSD was first released in the late 1970s and continues to have a strong following today exhibited in the continued existence of the above versions. The only exception is Sun who switched the design of their operating system over to System V Release 4.