The Act of Pawn Exchange
Pawns are often treated as defensive pieces, used as sacrifices in order to guard more "important" pieces on the board. But when a player uses a pawn for exchange purposes, the pawn suddenly becomes much more powerful. In order to ready a pawn for exchange with another piece, the player must advance it toward the last row on the game board. For white pieces, the goal is to reach rank 8. Black pawns are striving toward rank 1. Once the pawn reaches the final row on the board, it may be exchanged for another piece. As well as being known as "pawn exchange," this move is also called as "pawn conversion," "promotion" or "graduation."
Exchangeable Pieces
Pawns are often exchanged for queens when they are promoted, but players are not limited to this choice alone. A graduated pawn may be exchanged for a knight, bishop, rook or queen of the same color. A player is not required to exchange their pawn for a piece they have lost. For instance, if the player still has their queen intact but wishes to trade a promoted pawn for a queen this is perfectly acceptable.
When to Convert
Exchanging a pawn for a "dead" or captured chess piece is an important strategy, and the time of its usage in the game could be crucial. In the main, players use pawn exchange only toward the end of the game, in part because it takes several moves to advance a pawn all the way across the board. Begin moving pawns you hope to convert toward their goal during mid-play of the game, after the opening volleys have been fired. Often, it's best to lend support to potentially converting pawns with a bishop or rook. It's usually wise to attempt to send four of your eight pawns toward the end of the board. Of these, with enough skill and strategy, it's likely that you'll be able to exchange one or two.
Exchange Rules
Chess observes no limit when it comes to exchanging pawns. In theory, a player may advance all of their pawns and convert them all into more powerful pieces, though this is an improbable outcome. Only pawns may be exchanged for another piece; conversion does not apply to any other piece on the chess board. Pawns may turn into any other piece in the game, save the King.