I see it from time to time in boxing matches, though I don't know if it's an actual technique or just something for the moment. A boxer would take their stance and start bouncing from foot to foot. I was wondering how is it supposed to be done?

I don't think it should be done. You often see it in boxing matches, however, I think it is generally used just to help the boxer get into his "groove," like when boxers punch themselves lightly on the chin to prepare themselves for the actual bout.

There is far better footwork in boxing, which involves less bouncing and a more stable stance. The only time you want to be bouncing in a boxing bout is when you are on the outside throwing jabs, and even then, it's just not an effective way to box.

Ignore the bouncing, take a leaf out of the great defensive boxers' book- upper body moving, bobbing and weaving- that's the more effective defensive movement in boxing. Bouncing is bad- when TKD guys do it it's bad, don't give boxers any more credit for it.

I think its definately just to get you into a good motion, and get your rhythm going. If this is done, its usually done when not really in range of the opponent, think of the Ali shuffle, a showy version with the same ends.

IMO you should be as low to the ground as possible with footwork and should avoid hopping. Since you need to be on the ground to hit someone, and you cant move out the way as easily if your in the air, I think its best to stay on the ground as much as possible.