An endplay (also throw-in), in bridge, is a tactical play where a defender is put on lead at a strategic moment, and then has to make a play that loses one or more tricks. Most commonly the losing play either constitutes a free finesse, or else it gives declarer a ruff and discard.

Dealer: West. All Vul

J 9 7
Q 8 7 5
A K
A K 10 5
A K 10 8 6
K J 10
4 3
J 9 4
4 2
6 4 2
Q J 10 7 6
7 3 2
Q 5 3
A 9 3
9 8 5 2
Q 8 6
West North East South
1 Dbl Pass 1NT
Pass 2NT Pass 3NT
Pass Pass Pass

Opening lead: 8

Declarer won the lead and made four club tricks. West discarded the 10 and East a small heart on the fourth round.

Declarer then played out North’s A and K, and threw West in by leading the J. West was obliged after making his four spade tricks to concede two tricks in hearts.

You will observe that the throw-in is an end play. Generally speaking it is so; it usually occurs after the victim has been stripped of two or three of the suits and is obliged to lead towards a tenace or make other disadvantageous lead, such as giving a ruff and discard.