A customer service level agreement (SLA) is a mutually agreed-upon contract between a customer and a vendor that establishes expectations for the level of service the customer will receive. An SLA typically outlines the minimum acceptable service levels the customer can expect and any penalties the vendor may incur if they fail to meet those levels. From the customer's perspective, an SLA gives them a guarantee of minimum acceptable service levels. From the vendor's perspective, an SLA clarifies the customer's expectations and helps ensure that both parties work towards the same goal. An SLA is essential for ensuring that both customers and vendors are satisfied with the service level.