East Coast Swing (ECS) is a form of social partner dance derived primarily from the Eastern Swing Dance. Eastern Swing, in turn, evolved from Foxtrot or more specifically its leaping version known as Shag. Furthermore, East Coast Swing has been heavily influenced by Charleston and Lindy Hop.
This form of swing dance is strictly based in six-count patterns. The name East Coast Swing was coined to initially be a divider between the street form and the new variant used in the competitive ballroom arena (as well as separating the dance from West Coast Swing, which was developed in California).