Chess rules and strategy
Published · Updated
This page is the rulebook. If you have never played, read it top to bottom once and then start a game against the computer on Easy. If you already play, jump to castling, en passant, or the draw rules, which are the parts people most often get wrong. The board on the home page enforces every rule below, so you can test anything you are unsure about by trying it there.
The board and the starting position
Chess is played on 64 squares in eight rows and eight columns. The columns are called files and are lettered a to h from White's left. The rows are called ranks and are numbered 1 to 8 from White's side. Every square has a name made of its file and rank, such as e4 or g7. Set the board so that each player has a light square in the right-hand corner nearest to them. A quick check: h1 is a light square.
Each side starts with sixteen pieces: one king, one queen, two rooks, two bishops, two knights and eight pawns. The rooks go in the corners, the knights next to them, then the bishops. The queen stands on her own colour, so the white queen starts on d1 (a light square) and the black queen on d8 (a dark square). The kings go next to them, on e1 and e8. The pawns fill the second rank for White and the seventh rank for Black.
White always moves first. After that the players take turns, one move each. You cannot pass, and you cannot move twice in a row.
How each piece moves
King. One square in any direction: forward, back, sideways or diagonally. The king can never move to a square where it would be attacked. That one restriction shapes the whole game.
Queen. Any number of squares in a straight line along a rank, a file or a diagonal, as long as nothing is in the way. She combines the rook and the bishop and is the strongest piece.
Rook. Any number of squares along a rank or file. Rooks are slow to get into play because pawns and other pieces block them at the start, but in an open position or an endgame they are very strong.
Bishop. Any number of squares diagonally. A bishop stays on the colour it started on for the whole game, so each side has one light-squared and one dark-squared bishop.
Knight. Moves in an L shape: two squares in one direction and then one square at a right angle. It is the only piece that jumps over others, which is why it can leave the back rank before any pawn has moved. A knight always lands on a square of the opposite colour from where it started.
Pawn. Moves straight forward one square, or two squares on its very first move if both squares are empty. Pawns capture differently from how they move: one square diagonally forward. A pawn blocked by any piece directly in front of it cannot move straight ahead. Pawns never move backwards.
Every piece except the pawn captures the same way it moves: it lands on the square of an enemy piece and removes it. You can never capture your own pieces, and no piece except the knight can jump over another.
Check, checkmate and the goal
When a king is attacked, it is in check. The player in check must get out of it on the very next move, in one of three ways: move the king to a safe square, capture the checking piece, or put a piece between the king and the attacker (this last one is impossible against a knight or a pawn). You may never make a move that leaves your own king in check, and you may never move your king next to the enemy king.
If a king is in check and none of those three answers exists, it is checkmate and the game is over. The king is never actually captured. The shortest possible checkmate shows how little it can take:
1.f3 e5 2.g4 Qh4#
A player can also resign at any point, which ends the game as a win for the other side. In the online mode on this site there is a Resign button for that.
Castling
Castling is the one move where two of your pieces move at once. The king moves two squares toward a rook, and that rook jumps over to the square the king crossed. Castling on the king's side (written O-O) puts the white king on g1 and the rook on f1. Castling on the queen's side (O-O-O) puts the king on c1 and the rook on d1. Black castles the same way on the eighth rank.
You may castle only if all of these are true:
- Neither the king nor that rook has moved earlier in the game.
- Every square between them is empty.
- The king is not in check right now.
- The king does not pass through or land on a square that an enemy piece attacks.
The rook may pass through an attacked square; only the king's path matters. For queen-side castling this means b1 (or b8) may be attacked, but c1 and d1 may not. On this site you castle by selecting the king and then choosing the highlighted square two steps to the side.
1.e4 e5 2.Nf3 Nc6 3.Bc4 Bc5 4.O-O
En passant
This rule exists because pawns gained the two-square first move. If a pawn advances two squares and lands right beside an enemy pawn on the fifth rank (for White) or the fourth rank (for Black), that enemy pawn may capture it as if it had moved only one square. The capturing pawn moves diagonally to the square the other pawn skipped over. The capture must be made on the very next move, or the right is lost.
1.e4 Nf6 2.e5 d5 3.exd6
In the line above, Black's pawn went from d7 to d5 and landed next to the white pawn on e5. White answered 3.exd6, removing the pawn from d5. If White had played any other move first, the capture would no longer be available.
Promotion
A pawn that reaches the far rank is replaced at once by a queen, rook, bishop or knight of the same colour, chosen by its owner. It cannot stay a pawn or become a king. You can promote to a queen even if your first queen is still on the board, so two or three queens are legal. Most players choose a queen; a knight is occasionally better when it gives check or avoids stalemate. On this site a small window asks which piece you want.
How a game is drawn
Not every game has a winner. A draw happens in any of these ways, and this board recognises the first four on its own:
- Stalemate. The player to move is not in check but has no legal move. This is a draw, not a win, and it is the most painful way to throw away a won position.
- Threefold repetition. The same position, with the same player to move and the same castling and en passant rights, appears three times.
- The fifty-move rule. Fifty moves by each side pass with no capture and no pawn move.
- Insufficient material. Neither side has enough pieces left to checkmate, for example king against king, or king and one bishop against king.
- Agreement. Both players agree to a draw. Over a real board this is common; against the computer here it is not offered.
Reading chess notation
The move list beside the board uses standard algebraic notation. Each piece has a capital letter: K king, Q queen, R rook, B bishop, N knight. Pawns have no letter. A move is the piece letter plus the destination square, so Nf3 means a knight moves to f3 and e4 means a pawn moves to e4. An x means a capture (Bxf7), + means check, # means checkmate, and =Q means a pawn promotes to a queen. If two identical pieces could reach the same square, an extra file or rank letter shows which one moved, as in Nbd2. The move numbers count one move by White and one by Black as a single numbered move.
How to play this edition
Move your pieces to checkmate the opposing king. White moves first. Legal moves, castling, en passant and promotion are enforced, so the board will simply refuse an illegal move. Select a piece and the squares it can reach light up. A king may never remain in check.
A practical first plan
Before attacking, look for checks, captures and threats on both sides. Develop pieces toward useful squares and keep your king safe. A piece that attacks a square may still be needed to defend another piece; check what becomes exposed before moving it. The opening principles article turns this into a short routine for the first ten moves.
Computer or online?
Start against the computer on Easy, or pick Normal or Hard when you want a longer search for check. That match and its tally stay inside this browser. Online, the server keeps a move only when your own king is not left in check. Coming back to the page restores a game that is still underway. If ten minutes pass with the position unchanged, the online game closes.
Frequently asked questions
Can I invite a particular friend? A chess invitation only drops the other person into open matchmaking with strangers. It does not set a game aside, and it cannot line you up to castle against one named friend.
Can I undo an online move? Rewinding exists only for the computer opponent kept in this browser. Once an online move is accepted, an en passant capture included, neither player can remove it.
Are scores shared between devices? The AI scoreboard belongs to this browser. There is no global ranking or account sync.
More questions about the site and the game are answered in the chess FAQ.