A forcing to game bid is a bid indicating that both members of the partnership should keep bidding until they reach game.
Once a game-forcing situation is in place, the partners can take the bidding slowly to explore for the best contract, knowing that the other will not drop the bidding short of game.
Examples of bids that create a forcing to game situation in Acol are: a jump shift by opener or responder, opener’s reverse after a two-level response, fourth suit forcing at the three level, a 2♣ opening with a suit rebid.
Here is an example of a forcing to game bid in action:
West’s 2♠ creates a game force, allowing East to make a simple raise setting spades as trumps. If East had to jump to 4♠ over 2♠, it would be hard for West, looking at three fast heart losers, to explore for slam.