There are many sub-genre categories for the vast and general term Electronic or Electronica music. When tagging I like to categorize the terms as follows:
Sub-Genre: Ambient, Ethereal, New Age, Downtempo/Chill Out, Lounge
Sub-Genre: Techno, House, Deep House, Tech House, Progressive House, Electro House, Dubstep
Since the realm of Electronic music is ever changing and new sub-categories tend to pop up, it is helpful to stay informed of these specific styles and knowing some of the traits and influential artists that play major roles within these sub-genres.