What is a trapezoid?

A trapezoid is defined as a four-sided figure, or quadrilateral, that has at least one pair of parallel sides. This characteristic distinguishes trapezoids from other four-sided shapes, such as rectangles or squares, which have two pairs of parallel sides. The presence of only one pair of parallel sides allows trapezoids to have varying angles and lengths of the non-parallel sides, leading to different types of trapezoids, such as isosceles trapezoids where the non-parallel sides are of equal length. This understanding is fundamental in geometry and is essential for distinguishing trapezoids from other shapes, thereby solidifying the correct answer.