Suppose that partner opens 1. If you have 3-card spade support, you should raise his spades as follows:
The Single Raise. A single raise shows a minimum hand and 3-card support:
|1 2: 6-10 points and 3-card spade support.|
Partner should pass unless he has significant extra strength.
The Limit Raise. With an invitational hand, you should make a limit raise:
|1 3: 10 or 11 points and 3-card spade support.|
Partner should pass with only 13 points and bid 4 with 15 points. With 14 points, partner must choose between these two options.
The Preemptive Raise. Raising to game immediately is actually preemptive:
The Delayed Raise. With a game-forcing hand, you should begin by bidding a new suit, and then raise to game:
|1 2 2 4: 12+ points and 3-card spade support.|
You should not raise to game immediately, since such a bid would be preemptive!