Overcall

In a suit

• Promises at least a five card suit
• 8-16 at the 1 level
• 10-16 at the 2 level
• Double if you're too strong to make a direct overcall (17+). Then bid your suit later

Responses

• Support with a 3+ cards in your partner's suit
• Bidding a new suit shows 5+ cards and 10+ points
• Without a fit
  • pass with a weak hand (< 8 points)
  • Bid 1NT with 8-11, 2NT with 11-13
  • 3NT if you have enough points for game

1NT overcall

• 15-18 points
• NT shape
• Stopper in the opponent's suit (stop = A, Kx, Qxx of Jxxx)
• Do you have a stronger balanced hand? Then first double and then bid NT
• Partner can respond the same as after a NT opening.

Jump overcall

• six card suit (2-level) / 7-card: 3 level
• Shows a weak hand with one solid suit
• Can be dangerous to bid high!

Double

• You have an opening, but no suitable overcall
• You have support (3+ cards) in all other suits than the opener's suit
• Preferably, you have few cards in the opener's suit
• Partner will respond by bidding his best suit
• With very strong hands, you als start with double.