N

E

S

W

1♥

X

These are all standard takeout doubles. Opening hand or better, either with support for other suits or a strong single suited hand with 16 or more points.
The second double in the fourth example is still takeout. Usually any doubles where partner has not bid any suit or no trumps is for takeout, particularly when opponents have found a fit. The second double also implies that East does not have a five card suit.

1♥

P

2♥

X

1♥

P

P

X

1♥ P

X
X

2♥ P

P

1♦

P

P

X

2♦

P

East has less than opening hand values and no 5 card suit. Should have 

shortage in diamonds and at least three card support for the other suits.

1♦

1♥

?

Holding any 4 spades double showing 6 plus points and the 4 card spade suit and denying 5 spades. If have 5 or more spades bid 1S.

1♥

X

2♥

X

West’s double says pick your suit and implies doesn’t hold 5 spades

1♥

X

2♣

X

The second double says I have spades and diamonds. If have 5 spades bid it

1♣

1♦

X

South has one or both majors with 6 or more points. Possible club support

1♦

1♠

X

The classic negative double. Expect to have 4 hearts with 8 or more points.

1♥
X

X

XX

2♣

Redouble shows 10 or more points, usually without prime support for partner’s suit. All doubles by your side after this are for penalties

1NT

X

Showing good 15+ points. Partner can leave in with 7+ points. All doubles by E/W after this are for penalties

2♥

X

Takeout with opening hand or better. Partner can leave in with lots trumps

2♥

X

3♥

X

West’s double says take your pick partner

3♥

X

Takeout with 16 or more points. Again partner can leave in

4♥

X

Usually penalties. With a strong hand and long suit bid it.

1♥

1NT

2♦

X

Doubles after a NT overcall showing 15+ points are for penalties

1♥
3♥

1♠
P

2♥
P

2♠
X

As E/W have found a fit the double is for penalties