An octagon is a geometric shape that has eight sides and eight angles. The word "octagon" comes from the Greek words "okto," meaning eight, and "gonia," meaning angle. Regular octagons have equal sides and angles, while irregular octagons can have sides and angles of different lengths and measures. One of the most famous examples of an octagon is the stop sign, which is used in traffic control. The octagonal shape helps it stand out to drivers, making it easily recognizable. Octagons can also be found in architecture and design, adding unique visual interest to various structures.