In contract bridge, an overcall is a bid made after an opening bid has been made by an opponent; the term refers only to the first such bid. A direct overcall is such a bid made by the player seated immediately to the left of the opener, i.e. next in the bidding rotation; an overcall in the 'last seat', i.e. by the player to the right of opener, which is made after two intervening passes, is referred to as a balancing overcall.
The overcaller has one or more of the following objectives:
In most bidding systems, an overcall in an unbid suit is natural denoting length and strength in the suit bid. The common requirements include:
The rule of thumb is that the weaker a hand is in high card points, the better the bid suit should be (i.e., longer or with stronger honors).
According to modern bridge theory, the following hands warrant a 1♥ overcall over an opposing 1♣ or 1♦ opening:
♠ 632 ♥ AKJ96 ♦ 8752 ♣ 4
♠ A32 ♥ AKJ96 ♦ 752 ♣ 104
♠ A3 ♥ AK986 ♦ KQ5 ♣ 742
Stronger hands such as ♠ A3 ♥ AK986 ♦ KQ5 ♣ Q42 are considered too strong for an overcall, and should be bid via a takeout double followed by the most economical rebid in hearts.
Notrump overcalls at the one-level normally indicate 15-18 HCP in a balanced hand, with at least one stopper in opponent's suit. Usually, Stayman is on but transfers are off.