Book excerpt: For many decades, IT infrastructure has provided the foundation for successful application deployment. Yet, general knowledge of infrastructures is still not widespread. Experience shows that software developers, system administrators, and project managers often have little knowledge of the big influence IT infrastructures have on the performance, availability and security of software applications. This book explains the concepts, history, and implementation of IT infrastructures. Although many of books can be found on individual infrastructure building blocks, this is the first book to describe all of them: datacenters, servers, networks, storage, virtualization, operating systems, and end user devices. Whether you need an introduction to infrastructure technologies, a refresher course, or a study guide for a computer science class, you will find that the presented building blocks and concepts provide a solid foundation for understanding the complexity of today's IT infrastructures.