Castling is a special chess move that involves the king and one of the rooks. It allows the player to move the king two squares towards the rook, while the rook moves to the square next to the king on the opposite side. This move serves two purposes: it helps to protect the king by moving it to a safer position and connects the rooks for better coordination. To perform castling, certain conditions must be met. Neither the king nor the rook involved can have moved previously, and there must be no pieces between them. Additionally, the squares the king moves across must not be under attack, ensuring the move is safe.