This document provides background information on the design, application, repair and inspection of composite structures, including metal bonding, used on civil transport aircraft. The objective of this document is to assist inspectors to know where to expect composite and metal bonded parts on the aircraft, to understand the capabilities of current NDT methods and to aid interpretation of inspection results. This document does not contain inspection procedures. It is intended to be informative and should not be used singularly, that is, it does not override any instructions that may be issued within a manufacturer's or operator's published documentation.