A service level agreement (SLA) is a written contract between a service provider and a client that specifies the services to be provided and the expected level of service to be provided to the customer at all times. Vendors, services, and industries all have different agreements. Before subscribing to an IT service, the SLA should be thoroughly examined and tailored to maximize service value for both the end-user and the business. Service providers should note the distinctions between internal outputs and customer-facing results since they can assist in establishing service expectations. Service level agreements can cover/define a wide range of internal goals and KPIs.