The "stop-and-go" play refers to a strategy sometimes used to good effect by short-stacked players in tournaments. It's a two-part move that begins before the flop then continues on the flop — kind of a delayed all-in push of your short stack that gives you one other option besides simply going all in preflop.
By "short-stacked" we're referring to a chip stack of around 7-10 big blinds, although you could still try the stop-and-go with a little more or less. However, the play isn't really a viable option once you're down to five BBs or less.
Let's start out defining the play, then talk about some of the strategy involved when it comes to choosing the stop-and-go rather than simply shoving all in before the flop.