ideas apply to placing rooks on open files and knights on active, . The standard valuation is one point for a pawn, three points for a knight or bishop, five points for a rook, and nine points for a queen. These values are reliable in endgames, particularly with a limited number of pieces. But these values can change depending on the position or the phase of the game (opening, middle game, or ending). A for example, is worth an additional half-pawn on average. In specific circumstances, the values may be quite different: sometimes a knight can be more valuable than a queen if a particular angle is required for a mating attack, such as certain smothered mates. The humble pawn becomes more and more valuable the closer it is to securing a queen promotion for another example. History Chess evolved over time from its earliest versions in India and Persia to variants that spread both West and East. Pieces changed names and rules as well; the most notable changes was the Vizir (or Firz) becoming the Queen, and the Elephant becoming the Bishop in European versions of chess. The movement patterns for Queens and Bishops also changed, with the earliest rules restricting elephants to just two squares along a diagonal, but allowing them to "jump" (seen in the fairy chess piece the alfil); and the earliest versions of queens could only move a single square diagonally (the fairy chess piece Ferz). The modern bishop's movement was popularized in the 14th and 15th centuries, and the modern queen was popularized in the 15th and 16th centuries, with versions with the more powerful modern queen eclipsing older variants. Piece names The characters implied by pieces' names vary between languages. For example, in many languages, the piece known in English as the "knight" frequently translates as "horse", and the English "bishop" frequently translates as "elephant" in language areas that adapted the modern bishop's movement pattern, but not its new name. Variant pieces Chess variants sometimes include new, non-standard, or even old pieces. For example, Courier Chess, a predecessor of modern chess dating from the 12th century, was played on an 8×12 board and used all six modern chess piece types, plus three additional types of pieces: Courier, Mann (or rath or sage), and Jester. Variants of "old" chess might use the old rules for bishops/elephants with the alfil piece, or old rules for