Exchanging pieces is trading one of your pieces for an identically valued piece of your opponents. In terms of pieces, both you and your opponent, have lost an identical amount of firepower.

There is a tendency for many beginners to exchange pieces, while often more experienced players will tend to avoid this tendency. With exchanging pieces, it is difficult to say whether it is good or not; it really depends on the situation. You really need to consider the overall board configuration and flow of the game, and not just for the sake of exchanging pieces.

There are many times when it would be advantageous to exchange pieces. If a particular piece is heavily used by an opponent, and you can see that a particular piece forms the foundation for their offense or defensive strategy, then there is strong reason to perform an exchange. In doing so, you rob your opponent of a highly valued piece while losing your less valued, while identical, piece.

Exchanging pieces also holds value in accelerating the game. If you hold a numerical or strategic advantage over your opponent, then perhaps it may be beneficial to take as many pieces off the board as possible to wither your opponents army down, while maintaining your advantage.

It is well known that Rooks are more valuable in the end game than the mid game. Exchanging pawns will allow one to open up the board so that there is more room for one's Rooks to maneuver. This is especially beneficial if you hold more Rooks than your opponent.

In some instances, when an opponent offers you an exchange by threatening your (protected) piece with an identically valued piece of theirs, it maybe better to retreat. With more pieces at your disposal, you will have an easier time controlling the board, especially if you have the ability to coordinate your pieces well such that they are able to protect each other. You also must consider whether taking their piece with the protector will disrupt the coordination or your pieces. Moving one piece can leave many gaps in your defense, and it is imperative that one is aware of these gaps.