Abstract
This chapter provides an introduction to the generic types of constituents, manufacturing defects and in-service defects to be found in composite materials based on continuous fibres. First, the basic composite constituents are outlined. Next, fibre/matrix debonding, matrix cracking damage, fibre fractures and delaminations are discussed for simple fibre architectures in order to introduce some basic ideas relating to damage accumulation. Subsequent chapters of the book deal with more complex fibre architectures and/or types of loading, and elaborate on the strategies used for modelling damage accumulation.