This document aims to provide a basic understanding of the complex set of phenomena governing durability and long-term performance of concrete structures and how this forms a basis for service-life design. While consideration is given to concrete as a material, the focus is on the behaviour of the concrete structure and its interaction with its environment. This document should not only assist the designer to improve the future durability performance and reliability of concrete structures, but should also assist engineers involved with the assessment, maintenance and extension of life of existing concrete structures. The content in the book is also incorporated into a separate publication from fib, the International Federation for Structural Concrete, and is published in this separate volume in order to make it more widely available to concrete specialists and engineers worldwide.