ITIL® stands for Information Technology Infrastructure Library. As per ITIL® definition it comprises of six sets namely Service Support, Service Delivery, Planning to Implement Service Management, ICT Infrastructure Management, Applications Management and Business Perspective and best practices of IT managed service processes.
The ITIL® definition outlines its quality approach that helps in achieving more efficient and effective business processes. Of the complete ITIL® definition, if we talk about IT service management or ITSM, ITIL® comprises of two main sets: Service delivery and Service Support. These two components of ITIL® definition together comprise of 10 disciplines that allow provision and management of effective IT services.
Please note, that ITIL® definition nowhere states that it is a methodology, rather it is a set of standards and best ITSM practices.