Extrusion is a process used to create long sections of a uniform cross-sectional profile. The material is pushed or drawn through a die then cut to the required piece length. The material only encounters compressive and shear stresses so brittle materials with complex cross-sections can easily be created. Excellent surface finishing can be obtained with this operation. Extrusions can be formed while hot or cold and can have indefinite length. Commonly extruded materials include metals, polymers, ceramics, and foodstuffs.