An irregular polygon is any polygon that is not a regular polygon. It can have sides of any length and each interior angle can be any measure. They can be convex or concave, but all concave polygons are irregular since the interior angles cannot all be the same. If you drew a polygon at random, it would probably be irregular.
Specific irregular polygons such as a parallelogram have some interesting properties and have their own web pages.
|Vertex||The vertex (plural: vertices) is a corner of the polygon. In any polygon, the number of sides and vertices are always equal.|
|Side||The sides are the straight line segments that make up the polygon.|
|Area||There is no easy formula for the area of an irregular polygon, but see Area of a Irregular Polygon for some general approaches to the problem.|
|Perimeter||The sum of the lengths of the sides. See Perimeter of a polygon|