A service level agreement (SLA) is a contract between a service provider and the end user who will receive the service. A service level agreement is output based so it will only define the output the end user will be getting. It does not provide a roadmap of how that service will be delivered.
The various measures or metrics that are used to define the SLA are:
In practical scenario, Customers do not have practical knowledge of how the service works. So, they have various unrealistic expectations from the service. Customers gets frustrated when these expectations do not meet. A comprehensive SLA effectively manages these expectations by communicating the customer about the capabilities of the service provider. So, it eradicates the unrealistic expectations of the customers.
Customers don't have practical and technical knowledge of the service. So, theydo not understand how your service works. They just want to knowhow the service will affect them. So, the SLA lists all the issues that are likely to occur and what the immediate response will be and what measures will be taken to get it resolved if the response is not satisfactory.