What does a service always deliver to customers?

Applications are specific software tools that may support a service, but they are not what a service always delivers - they are an enabler of delivery, not the outcome itself.

Infrastructure is a resource used to deliver services, not the outcome that customers receive - services abstract infrastructure complexity away from customers.

ITIL's core definition states that a service is 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. Value is the fundamental and universal output of every service, regardless of the underlying technology or resources used to deliver it.

Resources are inputs consumed in service production, not the output delivered to customers - a service transforms resources into value for the customer.