How many sides does a quadrilateral have?

A quadrilateral is defined as a polygon that has four sides. The concept of a quadrilateral is fundamental in geometry and it is characterized by its four vertices and four edges. Common examples of quadrilaterals include squares, rectangles, trapezoids, and parallelograms, all of which illustrate the defining property of having four sides. Understanding this basic geometric principle is essential in various aspects of mathematics and helps students grasp more complex topics later on. The other options refer to polygons with different numbers of sides, which do not fit the definition of a quadrilateral.