At a macroscopic scale, a fiber alone can only support loads in tension. Under compression, a bare fiber would collapse like a rope and not support any load at all. Fibers can be combined with a secondary material that constrains the fiber to a specific shape and allows the fiber to support compressive loads. The material that supports the fiber is referred to as the matrix. The matrix encapsulates the fiber reinforcement and allows loads to be transferred between fibers. This combination of fiber and matrix forms a fiber-reinforced composite material.