Bridge base basic, also known as BBO basic, is a bidding system for the game of bridge based on Standard American Yellow Card. It is simplified, suitable for beginners, and widely used in internet bridge particularily on Bridge Base Online. It is taught in Fred Gitelman's educational software called Learn to Play Bridge that is available for free download from the American Contract Bridge League's website.

Key points of BBO Basic Bidding

Like SAYC, BBO basic depends upon hand evaluation using the high card point method. Hand shape djustments are made for long suits (1 point additional for every card longer than 4 in a suit) when bidding a new suit, and for short suits when showing support for partners bid (5 for a void, 3 for a singleton, and 1 for a doubleton).

Other similarities to SAYC include:

Five-card majors: opening a major suit promises a five-card suit.
Weak two bids: Two diamond, heart or spade openers are made with a six-card suit and 6 to 10 high-card points. Two of the top 3 honors are promised in that suit.
Strong two clubs: An artificial 2 call promosing 22 points or more.
Pre-emptive openers: including weak three bids (all suits except no-trump) and Weak four bids (minor suits only) similar to the weak two bids but showing additional length.
Notrump openers show a balanced hand (no void, no singleton, at most one doubleton, and may include a 5 card major) with the following point ranges:
- 1 NT = 15 to 17 points
- 2 NT = 20 to 21 points
- 3 NT = 25 to 27 points
Stayman and Jacoby Transfers conventions for no-trump openers
Blackwood or Gerber for slam bidding.

Opener approximate hand strengths

For unbalanced hands,

0 - 12 points: PASS
13 - 21 points: Hands of 13 points or more are strong enough to open with natural bidding.
22+ points: A hand in this range is shown to be very strong by using the strong 2 convention.

For balanced hands, open with a no-trump bid when you can limit your hand to the following point ranges:

1NT = balanced hand with 15-17 points
2NT = balanced hand with 20-21 points
3NT = balanced hand with 25-27 points

For other balanced hands, you can still limit your points by opening normally and then using the no-trump bid on your second bid:

13 - 14 points and a balanced hand, bid 1 with your longest suit and then bid 1NT
18 - 19 points and a balanced hand, bid 1 with your longest suit and then jump to 2NT
22 - 24 points and a balanced hand, bid 2 clubs and then 2NT
28 - 30 points and a balanced hand, bid 2 clubs and then jump to 3NT

Responder approximate hand strengths

0-5 points: A hand in this range normally should not bid (should pass) unless partner opens with the strong 2 convention.
6-9 points: This is a minimum response hand. You can show support for partners bid with a 2-level bid, or rebid a new suit at the one-level, and respond 1NT when no other bids are possible.
10 points: a new suit bid at the 2-level promises opening partner at least 10 points.

Responding with a minimum hand:

First priority is to show 3 card support for a partners 5 card major, rebid partners suit at the 2 level.
Next priority is to bid your longest suit if possible at the 1 level, promising at least 4 cards in that suit.
When possible, show support for partners minor suit opening if you have 5 card support (4 card support is acceptable but not preferred)
When you cannot support your partners bid, then your response is 1 NT, to show a bad fit and no more than 9 points (i.e. you deny ability to raise or bid a new suit). This gives partner the choice of passing and playing in 1 NT or changing to a partial game in another preferred trump suit (partner knows you are going to pass because you previously said you have 6-9 points).

Responding with a medium hand:

First priority is to show 3 card support for a partners 5 card major, so rebid partners suit at the 3 level. This limit raise is skipping the possible bid at the two level and jumping to the 3 level specifically to indicate that you have 10 or 11 points, an 8 card fit in partners major trump suit, and you are inviting your partner to a game bid if he has more than minimum opening strength. (opening bid promised a minimum of 13, and you have 10 or 11 for a sum or 23 or 24 points, very close to the game level of 25 points)
Next priority is to bid your longest suit if possible at the 1 level. You can show extra points with a 2 level bid later.
When possible, show support for partners minor suit opening with 5 card support (4 card support is acceptable but not preferred) but only at the 1 level. You can show extra points with a 2 level bid later.

Responding with a strong hand:

When you have 12 points or more (think 13 for partner to open plus 12 for you to respond is 25, game level for sure), then you have too many points for a single raise or a limit raise: you should bid a new suit first, and then come back and show support for partners previous bid at the next opportunity.
Use your new suit bid to show information about your hand to your partner, strong hand of course but also that you have CONTROL in another suit as well. Even if partner supports your long suit bid, remember to rebid your partners major suit bid on your second bidding opportunity.
Opening partner must think about how the hands may fit for a small slam.

Some special cases:

a pre-emptive bid to show support for partners 5 card major – when you have a minimum hand (6-9 points) and also excellent support for partners suit (meaning 5 card support for a major, 6 for a minor, and a side singleton or void so that those extra trump tricks can be used). The pre-emptive bid has a fair chance to make it, but even if it fails by one trick you are ahead because you successfully screwed up the opponents’ ability to achieve their own game contract.
a no-trump response to partners opening bid gives specific point information as well (so give this information to your partner, and then trust the next decision partner makes):
- response of 1NT means you have 6-9 points and no support for partners suit and no possible 4 card bid to make;( you already knew this from responding with a minimum hand: by the way, if you have no support for your partner but have 10 or eleven points, then bid your longest suit at the 2 level to show 10 points and then bid 2NT to invite the game to 3NT.)
- response of 2NT means you have 13-15 points and no support for partners suit and no possible 4 card bid to make;
- response of 3NT means you have 16-18 points and no support for partners’ suit and no possible 4 card bid to make.

References