A trapezoid is a four-sided shape with at least one pair of parallel sides. Imagine a rectangle that someone has slanted: the top and bottom remain parallel to each other, but the left and right sides now lean at angles instead of standing straight up and down.

You see trapezoids everywhere once you start looking. Many tables are wider at one end than the other, with trapezoid-shaped legs. Theater balconies often have a trapezoidal shape so more seats can fit while everyone still has a good view. The face of a cut diamond usually contains several trapezoid-shaped facets.

In math class, finding the area of a trapezoid uses a formula that averages the lengths of the two parallel sides. Carpenters and builders work with trapezoids constantly when cutting angles for staircases, roofs, and custom furniture.

When you picture a trapezoid standing on its longer parallel side, that longer side is called the base, while the shorter parallel side at the top is sometimes called the top or the other base. The slanted sides connecting them are simply called legs.