When you are playing an endgame, the number of acceptable or good moves gets narrower. This is because in the endgame you will get fewer pieces and the game starts to get tighter and every move and every tempo gets more important in every move.

There is a time when a player has no good moves and any move will be considered an error, this is the player would just like to “pass” the turn to the other player. Too bad for the player, in chess you must move a piece when it is your turn and you can not pass. When a player must move but he would want to “sit” in the position he is standing, he is said to be in Zungwang. Below there is an example defining the position very well.
Black is in zungwang position, he must move but he has no useful moves. Sooner or later white rook will move from a8 check and the a7 pawn will promote to queen. This example reflects the importance of passed pawns and also the importance of an active king in the endgame. The zungwang position must be considered a bad position for a player and it is a good strategy to force the other player to zungwang and, of course, avoid being in zungwang yourself.

Zungwang is impossible to take place in the opening game and very rare in the middlegame, but very usual in the endgame. Zungwang can only take place when there is a lack of material in the table or when there is a lack of good movements in the game. This is another difference between endgame and other stages of the game, the chance of getting stuck in zungwang position.

Only this move, which forces Black into a zugzwang, leads to a draw. If 4. Kxf6? Kd7 5. KfS Kc6 6. Ke4 Kc5 7. Kd3 Kd5, and Black is winning. Now, however, Black cannot make con­structive use of his material advantage. For example …

4…. Kd8 5. Kxd6 or 4…. f5 5. Kxf5 Kd7 6. Ke4 Kc6 7. Kd4

We arrive at a well known drawn position.

By forcing the other player to Zungwang a player can take advantage even when being in a lack of material.
This is another proof that, paradoxically, a chess game can end up without an endgame. The endgame is defined by an active king being favored, passed pawns getting more importance than in other stages of the game and the chance of zungwang. You should be wise in learning basic endgame techniques. Vassily Smyslov said that “the right endgame knowledge is the magic key to chess mastery.