Most organizations now produce and use a huge volume and variety of information on the internet and on their intranets. Many of these information resources have been designed and developed over the years as organizations have embraced and adapted to internet and web technologies. As a result, these resources are often not properly organized; in most cases information has been created and organized by a range of individuals, without full consideration of users and their requirements. This has caused enormous problems with finding and retrieving the correct information at the right time with the minimum effort. Fortunately the problem has been recognized, and many organizations now employ appropriate mechanisms for creating and organizing web and intranet information resources. The area of study concerned with the appropriate organization of web and intranet resources to facilitate easy access to, and management of, information is called ‘information architecture’ (IA). Library and information professionals are experienced in organizing information resources in accordance with user requirements, and consequently they have a great deal to contribute to the field of IA. This chapter provides an introduction to IA. First it describes what an IA is and what role it plays in the organization and processing of electronic information. It then goes on to discuss how to build an IA, detailing the stages involved, and outlines the expected outcome of an IA exercise.