Combination is a series of moves, in which pieces work together to bring about a sudden advantage.

The shortest way to a day of rest for the chess pieces is a sharp combination – Bronstein ( The Sorecerer’s Apprentice)

Here is a beautiful combination from Bronstien’s own game –

As it can be seen from the diagram, Queen And Rook combine together,and are attacking ‘g1′ square.The ideal position for black is Qg1#.So, how can black clear the path for his queen?. Another thing to notice in the position is White King stuck in the corner, g-file and e-files are open on which black rooks are well placed.The brilliant move Bd3!! wins the game.The rest of the game -
Qxd3 Rg1+(luring King to g1 square),Kxg1 e2+(discovered check by Queen and threat is Qf2 and mate)Ne3 Rxe3,Qf5+ Re6+(another discovered check by Queen) Kh1,Qf2(..white resigned)