It's a sideline triangle, created by a center in the post, a forward on the wing and a guard at the corner, leaving a two-man game on the weak side, run by a guard at the top of the key and a forward in the opposite-side, high-post position.
The triangle offense looks like a factory assembly line. It seems to chug. This guy goes there, that pass is thrown, and the cut is made. Interchangeable gears in a large machine, right? Just keep the conveyor belt moving until the whistle blows, fellas. You get a lunch break after 24 minutes.