
Star Trek, sometimes referred to as The Original Series (TOS): This show features the original starship Enterprise, helmed by Captain James T. Kirk. It ran from 1966 to 1969 for three seasons.

Star Trek: The Next Generation (TNG): This show takes place 100 years after the original series, and features the Enterprise-D and Captain Jean-Luc Picard. It ran from 1987-1994 for seven seasons.

Star Trek: Deep Space Nine (DS9) This show takes place during the same era as TNG, and is set aboard the starbase Deep Space 9, commanded by Captain Benjamin Sisko. It ran from 1993-1999 for seven seasons.

Star Trek: Voyager (VOY), This show, also in the TNG era, features the starship Voyager lost on the other side of the galaxy, trying to find its way back to Earth. Voyager was commanded by Captain Kathryn Janeway. It ran from 1995-2001 for seven seasons.

Star Trek Enterprise (ENT), known simply as Enterprise for seasons 1 and 2: This show was a prequel, taking place about a century before TOS, and featured a prototype starship Enterprise under Captain Jonathan Archer. It ran from 2001-2005 for four seasons.
Hmm, perhaps I'll dream of Star Trek tonight...