A polygon is a plane figure composed of a finite numbers of [[Line, Line-Segment, Ray|line-segments]] that are connected to form a *closed* [[polygonal chain]]. The segments are called edges, and their end-points/intersections are called vertices. Since two straight segments cannot form a closed chain, the smallest number of edges is 3. Polygons can be named by their number of sides. If a polygon has $n$ sides, we can call it an $n$-gon, or use their popular names. [[Triangle]] for $n=3$ [[Quadrilateral]] for $n=4$ [[Pentagon]] for $n=5$ [[Hexagon]] for $n=6$ [[Heptagon]] for $n=7$ [[Octagon]] for $n=8$ and more...