A service-level agreement (SLA) is the deal struck between a service provider and a client detailing the expectations and responsibilities of the provider. SLAs usually include components on reporting, responsiveness, incident management, and more so that client and provider are on the same page from the very beginning of an agreement.
The term SLA first appeared in the 1920s, but has evolved since then and now refers to this responsibility framework.
An SLA goes hand-in-hand with a contract to align with business objectives and ensure that when IT services are provided, whether to a client or interdepartmentally, all parties involved are aware of the services, metrics, and responsibilities expected of the service provider. This way, the service recipient knows exactly what they’re getting, and the provider knows exactly what they’re giving, leading to harmonious arrangements and clearly-defined service and management.