The rook

The rook moves horizontally or vertically, as many squares as it wants, as long as nothing blocks the path. It never jumps over a piece. If a friendly piece is in front of it, stop. If an opposing piece is on its line, it can capture it and stops on this square.

At the start of a game, rooks are often locked in the corners. They become really strong when files open, especially in the mid and late game. A rook on an open file is a bit like a car on the highway: finally space.