I visited Keith Rubow’s site again (because of the MP3s from the AACE convention) and liked this quote:

So what is the fascination of this activity? It is the endless variety of moves and formations. The caller gives the dancers a “call” to do. The dancers (all eight of them) have to figure out how to execute that call form the formation they are in, all while dancing to the beat of the music. There are countless formations (positions of the dancers) with names like lines, columns, boxes, diamonds, 1/4 tags, hourglasses, galaxies, butterflies and blocks to name just a few. The formation changes continually and flows from one formation to another as one call after another is executed to the beat of the music. At least that is the theory. Sometimes squares “break down”. This happens when one or more dancers fail to execute their part properly. Suddenly everyone is standing around wondering what happened. Oh well, just make lines, or square up and wait for the next sequence to start. It is expected (especially at the higher challenge levels) that no one can get it all. But it is so sweet when a square works well together and everything just “clicks”, nailing sequence after sequence.