Carbon fiber is a high-temperature resistant fiber with high strength and modulus. It is a high-end variety of chemical fiber. It is mainly composed of carbon atoms and is about 5-10 microns in diameter. To create carbon fibers, carbon atoms are bonded together in crystals, with the long axes of the fibers aligned parallel to each other giving carbon fibers a relatively high strength-to-volume ratio. Thousands of carbon fibers are bundled together to form a fiber bundle, which can be used individually or woven into fabrics.

The characteristics of carbon fiber, such as high hardness, high strength, light weight, high chemical resistance, high temperature resistance and low thermal expansion, make it very popular in aerospace engineering, civil engineering, military, racing and other competitive sports products. However, compared to similar fibers such as glass or plastic fibers, carbon fiber is quite expensive.

Carbon fiber is often combined with other materials to form composite materials. Carbon fiber-reinforced polymer (also commonly known as carbon fiber) that has a very high strength-to-weight ratio when mixed with plastic resins and wound or molded. However, carbon fiber is also compounded with other materials such as graphite to form high-temperature-resistant carbon-carbon composites.