Note that it describes the bourne shell, one of the most popular shells on UNIX - AFAIK any UNIX system should have a bourne shell installed, since it's mandated by the UNIX specification. The link also describes some of the differences between the bourne shell and the C shell.

I'm under the impression that the OP doesn't mean csh, but the command prompt on a Windows system, with the "C" being the default "C:\" prompt it shows when you fire it up.