A limit bid is a bid in which the bidder puts a tight upper limit on his point count. In natural systems, it is accomplished by bidding the highest contract which can be made given the information received from partner. For example, if partner shows 13 or more points with an opening of 1♥ and I have 10 points and heart support, I might bid 3♥, since together we have 23 points, in addition to whatever my partner has not yet disclosed, and that is roughly enough to make a 3-level suit contract.
More formally, the following three bids are almost always limit bids:
- Rebidding a previously mentioned suit (by either partner)
- Any NT bid
New suits are often unlimited. Once one partner has made a limit bid, the other partner is the captain and should try to set the final contract. Before any limit bids have been made, bids should be assumed to be forcing.