The term Jitterbug has several meanings depending on where you live. Originally Jitterbug was simply another regional name for the Lindy Hop that came into usage after about 1940. It is sometimes used, mostly along the west coast, to refer to a specific style of Lindy Hop still danced today.
Especially along the east side of North America, the term "Jitterbug" is often used as a name for a popular, fast, social Swing dance. It is usually a single step swing dance with a "quick, quick, slow, slow" rhythm.
This version of "Jitterbug" is widely danced as a social dance (often called "Jive" along the west side of North America). In the Arthur Murray syllabus it is known as the Single Step version of the Swing. This dance is discussed in the American Style Swing (East Coast Swing) section.