ITIL gives a detailed description of a number of important IT practices with comprehensive checklists, tasks and procedures that any IT organization can tailor to its needs. ITIL is published in a series of books, each of which covers an IT management topic.

The IT Infrastructure Library originated as a collection of books each covering a specific practice within IT Service Management. ITIL was built around a process-model based view of controlling and managing operations often credited to W. Edwards Deming and his PDCA cycle.

After the initial publication in 1989, the number of books quickly grew within ITIL v1 to over 30 volumes. In 2000/2001, to make ITIL more accessible (and affordable), ITIL v2 consolidated the publications into 8 logical 'sets' that grouped related process guidelines to match different aspects of IT management, applications, and services. However, the main focus was known as the Service Management sets (Service Support and Service Delivery) which were by far the most widely used, circulated, and understood of ITIL v2 publications. In 2006, the ITIL v2 glossary was published. In May 2007, the British Office of Government Commerce (OGC), an office of the UK Treasury, issued version 3 of ITIL (also known as the ITIL Refresh Project) consisting of 26 processes and functions, grouped under only 5 volumes, arranged around the concept of Service lifecycle structure.

ITIL Version 3 Description