A heptagon is a seven-sided figure, which is a polygon with seven sides and seven angles. It is a two-dimensional shape that is made up of straight lines and is often used in geometry. Heptagons are also known as septagons, and they can be regular or irregular depending on the length of each side. Heptagons are found in nature, such as in the shape of honeycombs, and they are also used in architecture and engineering.