Chess

Chess is a board game based solely on skill and tactics. It is played between two players on an eight-by-eight board with squares of alternating white and black. The object of the game is to trap the opponent's king so there is no possible escape from capture; this is called checkmate.

If a player cannot make a legal move (placing their king in check is not a legal move) but the king currently is not in check, the game is drawn (stalemate).

Originally from the Indian subcontinent and the Middle East, Chess (along with the Chinese/Japanese game Go) laid the foundations for strategy games, wargaming, role-playing games, and video games.

Object
The object of chess is simple. There are two players, one traditionally uses black pieces, while the other uses white pieces. Each player is given sixteen pieces, eight pawns, two rooks (also known as castles), two bishops, two knights, one king and one queen. The idea is to trap the king by taking turns to move your pieces around the board in a strategic manner. The player with the white pieces always goes first.

Pawn
The Pawn is the most basic chess piece. The pawn is allowed to move one space forward (or two from its starting position on the first move of the piece), and can only take other pieces diagonally. If they reach the opposite end of the board, they are replaced with any other piece except another king (owner's choice). Each player starts with eight of these pieces.

Rook
Rooks start at each end of the board. They can move any amount of squares horizontally or vertically, unless they are either blocked by a friendly piece or take a piece.

Knight
Knights are the most unusual pieces on the chess board. They must move three spaces in an L Shape. So either two vertically and one horizontally, or two horizontally and one vertically. They may only take pieces at the end of this movement. They are also allowed to pass over other pieces during this movement.

Bishop
Bishops are similar to the Rooks. However, they are only allowed to move diagonally.

Queen
Possibly the most versatile and considered by beginners to be paramount to winning a game of chess, Queens are able to move and take in any direction.

King
The target for each player. The aim is to trap this piece so it is unable to avoid being captured in any way. The King may only move one space in any direction (except when castling, see below). The King is the only piece that cannot be taken.

Castling
If the spaces between the king and one of the rooks (on the same side) are clear, this move can be performed by moving the king two spaces toward that rook and placing the corresponding rook on the other side of the king. However, castling cannot be done if the king has ever been moved during the game, and cannot involve any rooks that have ever moved during that game.

En Passant
A pawn can capture an opposing pawn in an en passant move if it has advanced two spaces to the square next to it in the previous turn.

History
Chess is believed to have originated in northwest India during the Gupta Empire, where its early form in the 6th century was known as chaturaṅga (four divisions [of the military] – infantry, cavalry, elephants, and chariotry, represented by the pieces that would evolve into the modern pawn, knight, bishop, and rook, respectively). According to both Chess historians Gerhard Josten and Isaak Linder "the early beginnings" of chess can be traced back to the Kushan Empire in ancient Afghanistan. The earliest evidence of chess is found in the neighboring Sassanid Persia around 600, where the game came to be known by the name chatrang. Chatrang is evoked in three epic romances written in Pahlavi (Middle Persian). Chatrang was taken up by the Muslim world after the Muslim conquest of Persia (633–644), where it was then named shatranj, with the pieces largely retaining their Persian names. In Spanish "shatranj" was rendered as ajedrez ("al-shatranj"), in Portuguese as xadrez, and in Greek as ζατρίκιον (zatrikion, which comes directly from the Persian chatrang), but in the rest of Europe it was replaced by versions of the Persian shāh ("king"), which was familiar as an exclamation and became the English words "check" and "chess". Murray theorized that Muslim traders came to European seaports with ornamental chess kings as curios before they brought the game of chess.

The Muslim Persians and Arabs developed the game's rules further, coming close to the modern game. A major change was the introduction of the checkmate, which added significantly more depth to the game. The earliest chesss manual was the Arabic text Kitab ash-Shatranj (Book of Chess) by Al-Adli ar-Rumi (800–870), a renowned Arab chess player.

The game reached Western Europe and Russia by at least three routes, the earliest being in the 9th century. By the year 1000 it had spread throughout Europe. Introduced into the Iberian Peninsula by the Muslim Moors in the 10th century, it was described in a famous 13th-century manuscript covering shatranj, backgammon, and dice, named the Libro de los juegos. Another theory contends that chess arose from the game xiangqi (Chinese chess) or one of its predecessors, although this has been contested.

Around 1200, the rules of shatranj started to be modified in southern Europe, and around 1475, several changes made the game essentially as it is known today. These modern rules for the basic moves had been adopted in Italy and Spain. Pawns gained the option of advancing two squares on their first move, while bishops and queens acquired their modern abilities. The queen replaced the earlier vizier chess piece towards the end of the 10th century and by the 15th century had become the most powerful piece; consequently modern chess was referred to as "Queen's Chess" or "Mad Queen Chess". These new rules quickly spread throughout western Europe. The rules about stalemate were finalized in the early 19th century. To distinguish it from its predecessors, this version of the rules is sometimes referred to as Western chess or international chess.