Chess terms

En Passant-
Immediately after a player moves a pawn two squares forward, and an opposing pawn can capture it if it moves one square forward. In this situation, the opposing pawn may capture the pawn as it passes through the first square. The resulting position is the same as if the pawn had only moved one square forward and the opposing pawn had captured normally
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Castle-
Castling is a special move involving the king and one rook.  Castling is where the king is moved two squares towards a rook on the player's first rank, then moving the rook onto the square over which the king crossed. Castling can only be done if the king has never moved, the rook involved has never moved, the squares between the king and the rook involved are not occupied, the king is not in check, and the king does not cross over or end on a square in which it would be in check.
Fianchetto-
A move when the pawn on B2 or G2 (white) or when the pawn on B7 or G7 (black) is moved one space forward and is filled by a bishop the next turn.

Pieces

Kings-
Kings should be used for defence, as the entire game is based on protecting it. However, don't forget that your king is capable of defending itself.

Queens-
Your queen is, by far, the most powerful piece. Try to not use it in the beginning unless your opponet uses it and only sacrifice it if your king is in check or if you can capture the enemy queen.

Bishops-
Bishops are valuable and are usually used to take care of opposing pawns and other stray enemies. Your bishops are useful throughout the game, mostly at the end.

Knights-
 The knights move in  L-shaped patterns and have the ability to jump over pieces, knights can be used to get hard-to-reach enemies. They should be used mostly at the begining of the game to quickly reduce the number of opposing pieces.

Rooks-
Rooks are usually used for defending the king. It is a good idea to castle during the middle of the game to protect your king. Two of these can protect your king from almost everything.

Pawns-
Use pawns to protect your more valuable pieces. However, if you manage to get your pawn to the other side of the board, you can transform it into a more valuable piece. So, 2 pawns that get to the other side could become two queens to terrorize the board.

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