A septagon is a flat shape with seven straight sides and seven corners (called vertices).

You've probably drawn pentagons (five sides) and hexagons (six sides) in math class. A septagon is simply the next shape in that sequence. Like its cousins, a septagon can be regular (with all sides and angles equal) or irregular (with sides and angles of different sizes).

Septagons appear less often in everyday life than shapes with fewer sides. You won't find many septagon-shaped buildings or common objects, though some unusual coins and architectural designs use this seven-sided form.

Sometimes people call this shape a heptagon instead, using the Greek word hepta (meaning seven). That name is more common in geometry classes and textbooks.