What should a service always deliver to customers?

Applications are a technical component that may be used to deliver a service but are not what a service delivers to the customer - many services involve no applications at all.

Infrastructure is an internal resource the service provider uses to produce and sustain services; it is not the thing delivered to customers as the result of consuming a service.

The ITIL definition of a service is 'a means of delivering value to customers by facilitating outcomes customers want to achieve without the ownership of specific costs and risks.' Value is therefore not an optional outcome but the defining purpose of any service - every ITIL process and lifecycle stage exists to ensure value is created, delivered, and maintained for the customer.

Resources are service assets used internally by the service provider to create value; they are inputs to service delivery, not the outcome that customers receive.