IT Service Management facilitates the design, creation, delivery, support, and oversight of IT service lifecycles, ensuring services align with business needs to deliver value. The IT Infrastructure Library is recognised for its comprehensive guidance and established practices among various frameworks for managing IT services.

The ITIL Service Lifecycle comprises five stages: Service Strategy, Service Design, Service Transition, Service Operation, and Continual Service Improvement. This lifecycle provides a systematic approach to managing IT services from inception to decommissioning.

Service Strategy involves:

• Defining service offerings and strategic objectives based on organisational goals and customer needs.
• Developing financial models and service portfolios to align IT investments with business objectives.
• Evaluating demand, capacity, and market conditions to make informed resource allocation decisions.
• Assessing potential risks and establishing risk management approaches.
• Establishing the value proposition for services and determining service priorities.

Service Design includes:

• Designing scalable, adaptable, and sustainable IT services, processes, and infrastructure.
• Addressing the Four Ps (People, Processes, Products, and Partners) to ensure smooth service delivery and transitions.
• Developing Service Level Agreements, availability plans, capacity plans, and security requirements.
• Creating technical architectures and service designs that integrate new services with existing systems.
• Ensuring compliance with regulatory and security requirements.

Service Transition focuses on:

• Planning, scheduling, and controlling service releases to minimise disruption.
• Testing and validating services to ensure they meet agreed requirements and performance standards.
• Managing service deployment and the transfer of services into the operational environment.
• Tracking and controlling changes using configuration management.
• Managing risks and issues that may arise during the transition phase.
• Decommissioning outdated services while integrating new or enhanced services into the live environment.

Service Operation is about:

• Supporting users by managing day-to-day operational activities.
• Monitoring and managing IT infrastructure and applications to deliver services effectively.
• Handling event management, incident management, request fulfilment, problem management, and access management.
• Monitoring and maintaining performance to meet agreed service levels.
• Ensuring the efficient use of resources to meet service requirements.

Continual Service Improvement targets:

• Analysing service performance data and feedback to identify areas for improvement.
• Implementing improvements across the service lifecycle based on performance assessments.
• Promoting the continuous evaluation of processes, services, and outcomes through quality management methods.
• Aligning services with evolving business needs and ensuring they remain relevant and effective.
• Fostering a culture of continuous improvement within the organisation.

ITIL Service Lifecycle Interdependencies

Service Strategy is central to the ITIL framework, establishing the foundation for all other stages through strategic decisions and policies. It ensures that actions in Service Design, Service Transition, Service Operation, and Continual Service Improvement align with organisational goals.

Service Design translates strategic objectives into detailed plans and service specifications.

Continual Service Improvement analyses performance data and feedback to identify areas for enhancement. It drives the iterative refinement of services, feeding insights back into the design process to ensure ongoing relevance and alignment with business needs.

Figure 1 below outlines each stage's contribution to the IT service lifecycle, supplemented by a simplified representation of the relationships between these stages.