Mandatory responses to takeout doubles

Your Partner who has just overcalled can have anything from 12HCP to over 20HCP.
The 3rd seat player didn't bid so you have to respond:

with a very weak hand, bid your best suit at the lowest level (even with 0HCP)
with a stronger hand (8-10HCP), give your 4-card suit with a jump and your 5-card suit with a double jump
Without a 4-card major and with stoppers in the opener's suit, look for a contract in NT.

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Problem E4869 The 3rd seat player passed so you have to bid. Here, 1♠ ... which doesn't promise very much !

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Problème E4869
The 3rd seat player passed so you have to respond. Bid 1 heart here, which doesn't promise much!

Responding with a suit

With 0-7HCP: the best suit at the lowest level giving priority to the majors.
With 8-10HCP:
- with a 4-card major or a 5-card minor, bid with a JUMP
- with a 5-card major bid with a DOUBLE JUMP
- with a 6-card major bid go to game
- With 11HCP or more cue bid the opener's suit to show strength.

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Problème E4873
You have to give your least feeble suit!

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Problème E4870
The lowest possible bid with only 7HCP.

Examples of responses with a suit
Be careful!
A jump and a double jump don't promise strong hands but respectively:

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Problème E4871
With more than 7HCP, a jump to show 4 ♥.

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Problème E5796
3 ♥, a double jump which shows 5 cards in that suit as well as 8-10HCP.

NT responses

They guarantee a stopper in the opener's suit and deny a 4-card major.

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Problème E4875
1NT with 7-9HCP and a diamond stopper.