A rectangle has four sides, four right angles, and opposite sides equal and parallel. The area is length times width. The perimeter is 2 × (length + width). A square is a special rectangle with all sides equal.

Rectangles are everywhere: books, screens, doors, windows, bricks. Their right angles make them easy to tile and stack. In geometry, the rectangle is a parallelogram with right angles. Diagonals of a rectangle are equal and bisect each other.

The rectangle is one of the simplest polygons and one of the most useful. Its properties are taught early and applied constantly. From architecture to pixel grids, the rectangle shapes the designed world.

• Quadrilateral with four right angles
• Opposite sides equal and parallel
• Area = length × width
• Square is a special rectangle