The term "two-step" describes several dances, some related to each other and some not. When the context doesn't indicate a particular two-step, the more complete name is generally used. Two-step dances include:
[country two-step]?
nightclub two-step (also called California two-step)
It also describes a subgenre of electronic dance music developed in the 1990s and which has become prominent in 2001.