In networks of computers, a host is a term for computers, on a network that do not forward traffic destined for other nodes. That is, nodes that are not routers can generally be said to be hosts, although the individual interfaces of routers have properties of hosts from at least an addressing perspective.
Common platforms:
Several versions of Windows (both workstation (aka PC) and server roles)
Unix, and derivatives such as
Linux, and further derivatives Ubuntu
BSD, and further derivatives such as modern versions of Apple Macintosh
Solaris
AIX