**Properties of Quadrilaterals**

A quadrilateral is a polygon with four sides. Quadrilaterals can be classified into several types based on their properties. Here are the properties of some common quadrilaterals:

**Square:**

- All sides are equal in length.
- All angles are right angles (90 degrees).
- The diagonals are perpendicular and bisect each other.

**Rectangle:**

- All sides are equal in length.
- Opposite angles are equal.
- The diagonals are perpendicular and bisect each other.

**Rhombus:**

- All sides are equal in length.
- Opposite angles are equal.
- The diagonals are perpendicular.

**Trapezoid:**

- Two sides are parallel and the other two sides are not parallel.
- The angles between the parallel sides are equal.

**Parallelogram:**

- Both pairs of opposite sides are parallel and equal in length.
- The opposite angles are equal.
- The diagonals bisect each other.

**Kite:**

- Two pairs of adjacent sides are equal in length.
- The opposite angles are equal.
- The diagonals are perpendicular.

In summary, a **quadrilateral** is a polygon with four sides.