A BitBoard is comprised of a 64-bit word, which is used to store the positions of different Chess Pieces.

Every square on a Chess Board is represented by one bit in the 64-bit word.

Since there are 12 different pieces in chess, 12 BitBoards are needed to store a chess position:

• whiteKing - bitboard with the position bit of the white king set to 1 (and other bits set to 0).
• whiteQueens - bitboard with the position bits of all white queens set to 1 (and other bits set to 0), etc
• whiteRooks
• whiteBishops
• whiteKnights
• whitePawns
• blackKing
• blackQueens
• blackRooks
• blackBishops
• blackKnights
• blackPawns

The bit-numbering convention for the bitboards:

• bit #0 will be the rightmost bit in the 64-bit word (least significant bit, or LSB), and
• bit #63 will be the leftmost bit in the 64-bit word (most significant bit, or MSB).
• Furthermore, square a1 = bit #0, h1 = bit #7, a8 = bit #56 and h8 = bit #63.