Some commonly-known shapes are squares, circles, triangles, stars and rectangles. There are many different kinds of polygons used in geometry and many shapes that combine or arrange multiple polygons to be used in designs.
Polygon is a geometric term that refers to a closed shape made of straight line segments. Some prominent polygons in ascending order of sides are the triangle, quadrilateral, pentagon, hexagon and octagon. Most polygons used in geometry are subdivided by more characteristics than just number of sides. For example, four-sided shapes (quadrilaterals) can be further divided into rectangles, squares, parallelograms, kites and trapezoids.
Shapes made out of curves are not considered polygons, although they are used in geometry. Circles are the best-known curved shapes, and pieces of circles are called sectors and segments. Ellipses are elongated circles.
In math, several shapes are not closed and are named after the kind of function that produces them. Open curves are often called parabolas of hyperbolas. An osculating curve resembling a wave might be described as a sine curve.
In daily life, many shapes are named after an object they resemble, such as a cross or star. Letters are also shapes and used to describe shapes, as in "v-shaped." Some shapes are associated with products and brands, such as the McDonald's arches or a Nike swoosh.