Chess is one of the oldest and most popular board games in the world. Over the last 1400 years chess has evolved from a military strategy tool into a gauge of human intelligence. It is played by two players whose goal is to checkmate the opponent's king.
Players take alternating turns to move their pieces on squares on an eight by eight checkerboard. The board can be divided into ‘files’ that run vertically denoted by letters, and ‘ranks’ which run horizontally, denoted by numbers. These coordinates create algebraic notation; a way of recording and describing moves.
Each player starts with a line of pawns along the second and seventh rank. On the first and eighth ranks each player will find their rooks (or castles), knights (or horses), bishops and their king and queen.
Pawns are the weakest piece, worth just one point. They can only move forward, one square at a time except for their first turn where they can move two. Although they move forward they capture on the forward diagonal. Should a pawn reach the end of the board it can be promoted to any piece.
Knight and bishops are the minor pieces, worth 3 points. Bishops can move diagonally any number of squares. Knights jump in small ‘L’ shapes; two up and one side or one up and two to the side. They are allowed to jump over pieces if needed.
Rooks are worth four points and they move laterally. The queen is the most powerful piece on the board, worth nine points.
They are a combination of rooks and bishops, moving any number of squares diagonally or laterally. The king is the most important piece on the board. They move the same as the queen but only move one square at a time.
To think about how pieces interact we can split the board up into squares that are empty and squares that are taken. Capturing a piece is when an opposing piece moves onto an occupied square; removing it from the board. To understand this we need to think about the vision of each piece based on the way it can move. Say we have a bishop on c3 and there is an opposing pawn on f6 our bishop can see d4, e5 and then the pawn on f6, it cannot ‘see’ any further than that.
When a piece ‘sees’ another piece then that one is in danger, we call this attacking. If the opponent also had a pawn on g7 then it ‘sees’ its teammate on f6, we would call this defending. When a piece is moved into a position that attacks a king this is called check. To escape a check the other player must move the king to a square that is safe, move another piece to intercept the vision or find a way to take the piece that is attacking it. If one player attacks the opposing king and there is no way to remove the check then this is checkmate.