The queen is the most powerful piece in chess: it combines the movements of the rook (straight lines along files and ranks) and the bishop (diagonals), allowing it to reach up to 27 squares in a single move from the center of the board.
Each side starts with one queen, placed on its own color: the white queen on d1 (a light square) and the black queen on d8 (a dark square). Its conventional value is around 9 points — slightly more than a rook (5 points) and a bishop (3 points) combined, reflecting the added versatility of controlling both diagonals and straight lines at once. Losing the queen without adequate compensation is almost always a decisive disadvantage.
In practice, the queen must be used with care. Bringing it out too early in the opening exposes it to attacks from less valuable enemy pieces (knights, bishops), forcing costly retreats and losing valuable time — so-called "tempi." The queen is most effective when activated after the other pieces are developed, working in coordination with the rest of the army.