Composites are materials made by combining two or more substances— one called the reinforcement and the other matrix— in such a way that the resultant product has better strength and property than the individual components. Weakness of one component is overcome by the strength of other component. Wood is the best example of a naturally occurring composite. It 
is composed of cellulose fibres as reinforcement in a lignin matrix. Similarly, in fibre-reinforced plastics glass fibre reinforcement is embedded in a plastic matrix to provide a much stronger product. The reinforcement, which could be a gas, particle or fibre, provides strength and stiffness to the composite. The matrix which could be any polymeric material, such as resin, or a metal or ceramic, holds the reinforcement and helps even distribution of the applied load within the composite. For best results the reinforcement and matrix should be compatible with each other. Normally, composites are made up of two dissimilar materials such as glass fibre and plastic but the same material can also be used both as the reinforcement and matrix, such as in ceramic-ceramic composites. Today, composites have become a part of our everyday life. They are also widely used in the aerospace industry as they provide an ideal combination of strength and light weight.