Understanding Takeout Doubles and the follow-ups is probably more important than any other part of bidding. They come up more often than any convention. This article is meant only as a brief overview and features 4 practice deals at the end. For a full explanation of the subject, please see :"Larry Teaches Doubles."
When your RHO opens the bidding in a suit (on any level), there are two basic kinds of "takeout" double:
1) Opening bid values with the "other 3" suits ("other 3" means at least 3 cards in each other suit)
2) 18+ points of playing strength and any distribution
Here are some examples of #1 when RHO opens 1:
, or AQ42
Here are some examples of #2 when RHO opens 1:
With the examples in #1, the takeout doubler will live with whatever his partner takes out to and not bid again! (Unless, of course, his partner invites by jumping). With the examples in #2, the takeout doubler clearly intends to bid again--whatever his partner does.
The partner of the takeout doubler jumps to invite (9-11) or can make sure of game with more (jump to game or cue-bid). Otherwise, he can bid 1NT (roughly 6-10) or make a minimum suit bid (0-8). For example, after 1 X P, the partner of the doubler bids:
1 with: J654
, 2 with: AQ76
, and 4 with: AJ765
Takeout doubles can be made in many situations (such as when the opponents have each bid, or in balancing position). It would take many pages to fully examine this subject, but this article is meant only as a review of the basics.
You might also consider getting Larry's book on Doubles and Redoubles HERE or try Michael's Doubles Webinar which you can find HERE.