There is no clear definition of when the endgame begins in a chess match, but it usually involves very few pieces remaining. A working knowledge of the unique implications of the endgame can help a player secure victory or, at the very least, turn a losing situation into a draw.
The power of pawns
First, the promotion opportunity makes pawns the highest endgame priority. Former world champion Max Euwe went so far as to maintain that two connected passed pawns on the sixth rank were equal in value to a rook. Being able to competently defend pawn chains is vital. The advantaged player should avoid exchanging pawns unless doing so helps him acquire a passed pawn or another tangible benefit.
Let the king pull your weight
Throughout the opening and middlegame, the king was a vulnerable liability to be protected. Consequently, some players make the mistake of continuing with this modus operandi until the end of the game. The king’s ability to move one square in any direction makes it very useful for weaving between groups of enemy pawns and eliminating them. The king is also a fundamental defensive tool. There are so few pieces left at the end of the game that relying on a lone knight, bishop, or rook to protect the pawns simply won’t work. Some theorists give the king a fighting value of four points, higher than minor pieces but lower than a rook. In short, moving the king toward the center of the board so it can be used to maximum effect is a critical endgame maneuver.
Taking the Initiative
Being the shot maker is more important now than at any other stage of the game. It’s better to have an active rook than one that’s stuck in a defensive role and an extra pawn or two. Having a well advanced king or passed pawn while the opponent is not are also situations that more than make up for a few pawns less.
zugzwang
Since only pawns and kings are left on the board, it is not uncommon for a situation to arise where a player would rather check than make a (disadvantageous) move. Such a scenario is formally called “zugzwang”. Exploring these cases to your advantage can sometimes turn the tide decisively.
Pulling a tie out of the jaws of defeat
Last but not least, trying to settle for a draw is a common endgame tactic that both players should be aware of. There are certain material imbalances that result in guaranteed draws. For example, two knights cannot checkmate a lone king because stalemate always occurs first. Another example is having the advantage of a bishop and a pawn. If the bishop fails to reach the pawn’s promotion square, a draw is inevitable.
