**ITIL** (Information Technology Infrastructure Library) is a globally recognized framework of [[Best practice|best practices]] for [[IT service management|IT service management]] (ITSM) that provides guidance on aligning IT services with the needs of business. Originally developed by the [[Central Computer and Telecommunications Agency]] (CCTA) of the [[UK government|UK government]] in the late 1980s, ITIL offers a structured, process-oriented approach to designing, delivering, managing, and continually improving IT services across the full service lifecycle. It is the most widely adopted ITSM framework in the world and has influenced the development of related standards including [[ISO/IEC 20000]], the international standard for IT service management. ITIL has undergone several major revisions since its initial publication. The original library comprised a large set of books covering various aspects of IT operations and service delivery. ITIL v2, published in the early 2000s, reorganized the framework around two core disciplines: [[Service support|Service Support]] and [[Service delivery|Service Delivery]]. ITIL v3, introduced in 2007 and updated in 2011, restructured the framework around a [[Service lifecycle|service lifecycle]] model comprising five phases: Service Strategy, Service Design, Service Transition, Service Operation, and Continual Service Improvement, each supported by a dedicated publication. **ITIL 4**, released in 2019, represents the most recent iteration and introduces the [[Service value system|Service Value System]] (SVS) and [[Service value chain|Service Value Chain]] as central organizing concepts, incorporating principles drawn from [[Agile software development|Agile]], [[DevOps|DevOps]], and [[Lean manufacturing|Lean]] methodologies to address modern digital service environments. ITIL 4 defines 34 management practices organized into three categories: general management practices, service management practices, and technical management practices. Core practices include [[Incident management (ITSM)|incident management]], [[Problem management|problem management]], [[Change enablement|change enablement]], [[Service desk|service desk]], [[Service level management|service level management]], and [[Configuration management|service configuration management]], among others. ITIL certification is offered at multiple levels—Foundation, Practitioner, Specialist, Strategist, and Leader—through accredited examination bodies including [[Axelos|AXELOS]], which has owned and managed the ITIL framework since 2013 as a joint venture between the UK government and [[Capita]]. ITIL certifications are widely pursued by [[IT professional|IT professionals]] globally and are commonly required or preferred in enterprise ITSM roles.