The IT Infrastructure Library (ITIL) framework consists of five books (sometimes referred as a stages) that are part of every IT service. Each stage contains several core processes or functions that are aligned with IT organization structure. Usually, companies adopt some of these processes, that are suitable for their teams but it is not required to implement the whole set of processes from all stages. Therefore, ITIL is quite flexible regarding adoption.

The following is a diagram of the ITIL service life cycle stages:

Core ITIL Processes:

• Service Strategy
• Service Design
• Service Transition
• Service Operation
• Continual Service Improvement