What is a volley in tennis?

At the net there's no time for a backswing, so the volley uses the incoming pace: a firm wrist, a short forward move and the racquet face set early. Most players use a continental grip so both sides work without changing grip.

Questions

What grip do you use for a volley?

Most players use the continental grip, which works on both sides without a change.

What is a half volley?

A shot hit just after the bounce, when the ball is still low.