Rooks

The rook is worth about five pawns. In general, rooks are stronger than bishops or knights and are considered greater in value than either of those pieces by nearly two pawns, but less valuable than two minor pieces by approximately a pawn. Two rooks are generally considered to be worth slightly more than a queen (see chess piece relative value).[7] Winning a rook for a bishop or knight is referred to as winning the exchange. Rooks and queens are called major pieces or heavy pieces, as opposed to bishops and knights, the minor pieces.[8] 

A common strategic goal is to develop a rook on the first rank of an open file (i.e., one unobstructed by pawns of either player) or a half-open file (i.e., one unobstructed by friendly pawns). From this position, the rook is relatively unexposed to risk but can exert control on every square on the file. If one file is particularly important, a player might advance one rook on it, then position the other rook behind—doubling the rooks.

A rook on the seventh rank (the opponent's second rank) is typically very powerful, as it threatens the opponent's unadvanced pawns and hems in the enemy king. A rook on the seventh rank is often considered sufficient compensation for a pawn.[9] In the diagrammed position from a game between Lev Polugaevsky and Larry Evans,[10] the rook on the seventh rank enables White to draw, despite being a pawn down.[11]

Two rooks on the seventh rank are often enough to force victory by the blind swine mate, or at least a draw by perpetual check.[12] 

Rooks are most powerful towards the end of a game (i.e., the endgame), when they can move unobstructed by pawns and control large numbers of squares. They are somewhat clumsy at restraining enemy pawns from advancing towards promotion unless they can occupy the file behind the advancing pawn. As well, a rook best supports a friendly pawn towards promotion from behind it on the same file (see Tarrasch rule).

In a position with a rook and one or two minor pieces versus two rooks, generally in addition to pawns, and possibly other pieces, Lev Alburt advises that the player with the single rook should avoid exchanging the rook for one of his opponent's rooks.[13]

The rook is adept at delivering checkmate. Below are a few examples of rook checkmates that are easy to force. A single rook can force checkmate while a single minor piece cannot.In the opening, the rooks are blocked in by other pieces and cannot immediately participate in the game, so it is usually desirable to connect one's rooks on the first rank by castling and then clearing all pieces except the king and rooks from the first rank. In that position, the rooks support each other and can more easily move to occupy and control the most favorable files.