A pentagon is a five-sided polygon, which means it has five straight edges and five corners, or vertices. The sum of the interior angles in a pentagon is 540 degrees. Regular pentagons have equal sides and angles, with each interior angle measuring 108 degrees. Pentagons can be found in various shapes and sizes, both in nature and human-made structures. For example, the United States Department of Defense building, known as the Pentagon, is a famous architectural example of a pentagon shape. Pentagons are also used in art, design, and geometry, making them an important shape in mathematics.