ITIL encompasses a framework of five core publications or ITIL books, which are periodically reviewed and updated as technologies change. Each book collects best practices for each major phase of the IT service lifecycle. ITIL Service Strategy explains business goals and customer requirements. ITIL Service Design shows how to move strategies into plans that help the business. ITIL Service Transition shows how to introduce services into the environment. ITIL Service Operation explains how to manage the IT services. ITIL Continual Service Improvement helps adopters evaluate and plan large and small improvements to IT services.
ITIL-based IT infrastructure management can be a complex specialty for any business, and is often the domain of the largest IT-centric businesses such as Microsoft, Hewlett-Packard and IBM, along with other major enterprises in retail, finance, pharmaceuticals, entertainment and manufacturing. ITIL adoption and maintenance normally requires trained and certified experts to guide a company and its IT staff.