There are a number of types of curbs, categorized by shape, material, height, and whether the curb is combined with a gutter. Most curbs are constructed separately from the pavement, and the gutter is formed at the joint between the roadway and the curb. Combined curbs and gutters (also called "curb and channel") has a concrete curb and gutter cast together in one piece. "Integral curb" is curbing constructed integrally as a part of a concrete pavement.