The ITIL (IT Infrastructure Library) consists of 5 volumes: Service Strategy, Service Design, Service Transition, Service Operation, and Continual Service Improvement. Although the UK Government originally created the ITIL, it has rapidly been adopted across the world as the standard for best practice in the provision of information technology services. As IT services become more closely aligned and integrated with the business, ITIL assists in establishing a business management approach and discipline to IT Service Management, stressing the complementary aspects of running IT like a business. Service Management is a set of specialized organizational capabilities for providing value to customers in the form of services. The core of Service Management is transforming resources into valuable services

Version 2 of ITIL consisted of 7 sets: Service Support, Service Delivery, Planning to Implement Service Management, ICT Infrastructure Management, Applications Management, Security Management, and The Business Perspective. However, the main focus was generally divided into two main areas, known as ITIL Service Delivery and ITIL Service Support.
Service Delivery is the management of the IT services themselves, and involves a number of management practices to ensure that IT services are provided as agreed between the Service Provider and the Customer. It includes 5 disciplines: Service Level Management, Capacity Management, Continuity Management, Availability Management, and IT Financial Management.
Service Support is the practice of those disciplines that enable IT Services to be provided effectively. The 6 Service Support disciplines are: Configuration Management, Incident Management, Problem Management, Change Management, Service/Help Desk and Release Management.

Service Delivery is the management of the IT services themselves, and involves a number of management practices to ensure that IT services are provided as agreed between the Service Provider and the Customer. Service Delivery consists of 5 disciplines. These are: Service Level Management, Capacity Management, Contingency Planning, Availability Management and IT Financial Management.

Service Support is the practice of those disciplines that enable IT Services to be provided. Without these disciplines, it would be almost impossible to provide these IT Services, and at best in a very unmanaged and haphazard way. The 6 Service Support disciplines are: Configuration Management, Problem Management, Incident Management, Change Management, Service / Help Desk and Release Management.

ITIL 3 (published on May 30, 2007) has the aim of bringing the twenty years old best practice guide up to date with current terms and trends and making it easier to use for the growing number of ITIL supporters. The refresh is led by Sharon Taylor, Chief Architect of the ITIL Refresh. BSI (the British Standards body) are involved in the refresh to ensure that ITIL and ISO 20000 are kept in line with each other. The refresh will begin with the publication of five new core texts (below) that will replace the current volumes: Service Strategy, Service Design, Service Transition, Service Operation and Continual Service Improvement.