Short answer
ITIL is a set of practices for managing IT and other services. In ITIL 4, a service is described as a means of enabling value co-creation by facilitating outcomes that customers want to achieve, without the customer having to manage specific costs and risks. In plain English: a service does something useful for someone, and the provider handles the hard parts.
The ITIL definition of a service
The wording sounds abstract, so it helps to break it into four ideas.
- Value: the benefit, usefulness or importance that someone gets.
- Outcome: the result the customer wants, such as being able to send invoices or answer customer calls.
- Costs: what the customer would otherwise spend to get that result, including money and effort.
- Risks: the uncertainty and potential problems the customer would otherwise carry.
A service lets the customer get the outcome while the provider takes on certain costs and risks. “Co-creation” means value comes from provider and customer working together, not from the provider alone.
Business service vs IT service
Terminology varies between organisations, but a common distinction is:
- A business service is something the organisation provides to its customers or uses to run its operations, such as online ordering or payroll.
- An IT service is the technology capability that supports it, such as hosting, networking or an application.
One business service often depends on several IT services working together. Describing services in business terms helps non-technical staff understand what is being delivered and why it matters.
Example
Take “online ordering” as a business service. Customers want to browse and buy easily. Behind the scenes, it relies on a website, a payment system, databases and support staff. The customer does not manage those costs or risks; the business provides the service and takes care of them.
Service definition in practice
A written service definition commonly covers:
- what the service is and who uses it
- the outcomes it supports
- what is included and excluded
- support hours and how to request help
- targets, often set out in a service level agreement (workforce management terms defines service level terms)
- an owner who is responsible for it
- dependencies on other services, which also feed a business impact analysis
Keep the language simple and focused on what the customer experiences. Organisations that keep a list of their services, often called a service catalogue, typically build it from definitions like these.
ITIL stages and relevance
The question “what are the 5 stages of ITIL?” refers to the service lifecycle in ITIL version 3: service strategy, service design, service transition, service operation and continual service improvement.
ITIL 4 reorganised the guidance around a service value system and a service value chain, with activities such as plan, improve, engage, design and transition, obtain or build, and deliver and support. Whether ITIL suits a given organisation depends on its size, industry and approach, and many teams adopt parts of it rather than all of it.
FAQ
How does ITIL define a service? As a way of enabling value by helping customers reach desired outcomes without managing specific costs and risks.
What is the definition of a business service? A service that supports a business function or is offered to customers, described in terms of the outcome it delivers.
Is ITIL still used? Many organisations still use it, often alongside other approaches. Check the current ITIL guidance from its publisher for details.
Terms like this are part of everyday workplace language; see our English business terminology glossary for more.