6-Count Swing is also known to people as "East Coast Swing" or "Jitterbug" and can be danced to most Big Band, 50s Rock & Roll or really anything that "swings". It is a 6 count pattern that repeats usually starting with a rock step (although ballrooms that teach this pattern will end with the rock step). The 3 different rhythms used for Jitterbug is a single step, kick step, and triple step. These rhythms can be used individually or mixed within the 6 count pattern. Dancers typically begin with this Swing Dance style as it tends to be the easiest to learn.
The origin of the term Jitterbug means different things to different people. Some say it referred to a drunk person having the "jitters" and others think it came from dancers that had exaggerated movements, let loose, and jumped around without any control. The name gained popularity when used by Cab Calloway in the film "Jitterbug Party" as well as the song "Call Of The Jitterbug" in 1935.
The specific 6 count pattern of the Jitterbug/East Coast Swing is said to have come from Arthur Murray, who thought it would be easier for people to learn a simplified 6 count pattern instead of dances like the 8 count Lindy Hop.