3D modelling is the process of using software to create a mathematical representation of a 3-dimensional object or shape. The created object is called a 3D model and these 3-dimensional models are used in a variety of industries. The film, television, video games, architecture, construction, product development, science and medical industries all use 3D models to visualise, simulate and render graphic designs. Polygon modelling Polygons are straight-sided shapes, defined by 3-dimensional points (vertexes) and the straight lines that connect them (edges). Modellers who use polygons usually use 3-sided polygons called triangles or 4-sided polygons called quadrilaterals. Polygonal surfaces have a wide range of applications and are the preferred surface type for animated effects in film, video game design (US site) and 3D web development. Curves and NURBS modelling NURBS, which stands for Non-Uniform Rational B-Splines, are composed of curves and are defined by a mathematical formula. NURBS are best used for modelling smooth surfaces with complex curves, such as a wineglass or a football. NURBs are more widely used in industrial or mechanical design.