The Plymouth Division of Chrysler Motors began July 7, 1928. It was to be the competition to Chevrolet (General Motors) and Ford.
For most of the time of Plymouth's existence, the line was nothing more than stripped, cheap (you know you never use that term in advertising!) versions of the more impressive Chryslers. It was also in the shadow of Dodge, which Chrysler bought a few weeks after the inception of Plymouth.
Plymouth eventually got some of its own livery, however it was not always looked as favorably as history makes it look.
Probably the best thing the company did was link arms with Warner Brothers cartoons to create the Road Runner sports car in the late 1960s. The Barracuda was also a very favorably received vehicle.
But many of its line were low priced versions of Chryslers. The last successful Plymouth was the PT Cruiser (PT for "panel truck"). Marketed as a Chrysler outside the United States, after the division died, it became a Chrysler soon thereafter.
Plymouth died after the 2001 model year.