Opener’s Rebid is a very important bid because it gives partner more information about the distribution of opener’s hand.  Even more importantly, opener’s rebid limits opener’s hand to a more narrow range of points.  When opener opens the bidding, she can have up to 21 HCP.  However, opener’s rebid limits her points to a certain range.  With this information, responder can add her points to opener’s points and then determine whether or not the partnership has enough points to try for the game bonus.  There are three general ranges for opener’s rebid:

• Minimum = up to 15
• Medium (game invitational) =16-18
• Maximum (game forcing) = 19-21

There are also only a few types of distribution that you can have:
• Support for partner = 4-card support for partner’s major suit
• Balanced = no singleton or void
• Single-suit = where you have one long suit of 6 or more cards
• Two-suited = where you have at least one 4+ card suit in addition to the one you bid in the opening bid

• Min = Make the minimum raise to 2 (about 12-15, 7 losers)
• Med = Jump raise to 3 (about 16-18, 6 losers)
• Max = Jump to game in partner's suit (19 -21, 5 losers)

Anytime you hold a balanced hand (no singleton, no 5-card major), you can show your strength and your shape at your first bid or your first rebid:  Here is how it goes:
• 12-14 points = open 1 of a suit and rebid 1NT (or the lowest level of NT over partners bid or pass over RHO’s bid)
• 15-17 points = open 1NT
• 18-19 points = open 1 of a suit and jump rebid in NT.
• 20-21 points = open 2NT
• 22-24 points = open 2♣ and rebid 2NT
• 25-27 points = open 2♣ and rebid 3NT

When you hold a 6-card suit, you can rebid it. Here are the rebids with various strengths:
• Min = Rebid 2 (about 12-15)
• Med = Rebid 3 (about 16-18)
• Max = Jump to game in a major or 3NT in a minor (18+ -21)

• Min & Med = Bid 2nd suit at the 2-level (about 12-17)
• Max = Jump shift to 2nd suit at the 3-level (18-21)

Many players have trouble with the concept of Reverses.  The first problem is the name.  To keep this bid in the same general idea as the Jump Shift, which shows a maximum hand, Reverses should be called something like “Voluntary 2-level Higher Shifts”.  Just to clarify things, however, it was originally called a Reverse because with a Reverse you reverse the order in which you normally bid suits.  Normally you bid your higher ranking 1st suit at the 1-level and your lower ranking 2nd suit at the 2-level so that partner can pass you in your lower suit or correct back to your higher suit without getting above the 2-level.  However, with a Reverse, you voluntarily bid at the two-level in a suit higher than the one you opened in at the 1-level.  This has to show extra points because why would you voluntarily force partner to the 3-level by mentioning a suit she has already chosen not to bid at the 1-level, unless you have extra points.

So the rules for Reverses are:
• A Reverse is when you rebid at the 2-level in a suit higher than the one you opened when responder only bid at the one level.;
• A Reverse shows 5+ cards in the first-bid lower-ranking suit and at least 4 cards in the second, higher- ranking suit bid at the 2-level; the first suit is always longer than the second;
• The high card point range is generally between 16 to 21 HCP; and
• Reverses are 100% forcing for 1 round

Not Reverses:
1♦ – 2♣ -2♥; 1♥ – 2♣ – 2♠; 1♥ - 2♦ – 2♠.  These auctions are NOT Reverses, because partner forced you to bid at the 2-level.  Your 2-level rebid in a higher suit must be over responder's one-level bid.  If responder has already bid on the two level, your bid is NOT a Reverse.