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So what is ITIL (Information Technology Infrastructure Library)?
ITIL is recognized worldwide as a best-practice approach for delivering IT services and IT service management. It focuses on the processes, functions, and capabilities required to support IT services in business.
Key terms to understand ITIL
Best-practice approach:
Best practices are available in a variety of sources, and ITIL is one of them. ITIL should be used in association with other best-practice approaches.
- Proprietary knowledge/internal experience
- Standards/industry practices
- Training and education/academic research
IT service:
An IT service is made up of a combination of information technology, people and processes. A customer-facing IT service directly supports the business processes of
one or more customers and its service level targets should be defined in a service level agreement. Other IT services, called supporting services, are not directly used by the business but are required by the service provider to deliver customer-facing services.
IT service management (ITSM):
The implementation and management of quality IT services that meet the needs of the business. IT service management is performed by IT service providers through an appropriate mix of people, process and information technology.
Process
A process is a structured set of activities designed to accomplish a specific objective. A process takes one or more defined inputs and turns them into defined outputs.
Function
A function is defined by ITIL as a team or group of people and the other resources or tools that are used to carry out a process or process activities.
You can find other definitions For ITIL from various sources
AXELOS
“A set of best-practice publications for IT service management. Owned by the Cabinet Office (part of HM Government), ITIL gives guidance on the provision of quality IT services and the processes, functions and other capabilities needed to support them. The ITIL framework is based on a service lifecycle and consists of five lifecycle stages (service strategy, service design, service transition, service operation and continual service improvement), each of which has its own supporting publication. There is also a set of complementary ITIL publications providing guidance specific to industry sectors, organization types, operating models and technology architectures.” https://www.axelos.com/corporate/media/files/glossaries/itil_2011_glossary_gb-v1-0.pdf
Gartner
“ITIL (formerly known as the Information Technology Infrastructure Library) is an IT service management framework owned by Axelos — a joint venture between the U.K. government and Capita. ITIL is structured as five core books to cover the full-service life cycle: service strategy, service design, service transition, service operation and continual service improvement.”
Wikipedia
“ITIL, formally an acronym for Information Technology Infrastructure Library, is a set of practices for IT service management (ITSM) that focuses on aligning IT services with the needs of business. In its current form (known as ITIL V3), ITIL is published as a series of five core volumes, each of which covers a different ITSM lifecycle stage.”
There are three main reasons why ITIL is successful and practiced all around the world…
- Vendor Neutral
- Best practices
- Non prescriptive
The factors that motivate organizations to adopt the framework:
- Creation of value for customers through the services provided
- Management of the investment for IT services and budgetary controls
- Risk management in alignment with the business
- Knowledge management across the service management enterprise
- Improvement in the interaction and relationship between the service provider and their customers
- The ability to coordinate the delivery of goods and services and to be able to optimize and reduce cost
- The adoption of a standard approach to service management across the organization
- The ability to measure, monitor, and optimize IT services and the performance of service providers
There are five ITIL publications:

Service Strategy: This covers the core of the life cycle, setting the strategic approach for service management activities.
Service Design: This provides guidance on the design and development of services according to the requirements of the customer and the strategic approach.
Service Transition: This provides guidance on the transition of new or changed services into the live environment, including the development and improvement of capabilities.
Service Operation: This covers the management of the day-to-day delivery of services, including optimizing effectiveness and efficiency.
Continual Service Improvement: This provides guidance on the maintenance of value creation and continual alignment to changing business needs.
ITIL in brief