A composite material is made up of a matrix and a reinforcement phase. Composites take advantage of directional properties of the reinforcement phase and gluing properties of the matrix. The reinforcement phase may be any material in fiber, platelet, or aggregate form. The matrix phase must be able to flow around the reinforcement and later hardened. Metals, ceramics, cement, and polymers are all regularly used for man-made composites. Composites are very difficult to manufacture (except for concrete). New techniques has made it easier to make sporting equipment, space shuttle parts, and car parts out of composites.