A Service Level Agreement (SLA) is a formal document that outlines the expected level of service between a service provider and a client. It specifies the services to be provided, the performance standards, and the responsibilities of both parties. SLAs are commonly used in various industries, including IT and telecommunications, to ensure clarity and accountability. SLAs often include metrics for measuring service performance, such as response times, uptime guarantees, and issue resolution times. They serve as a reference point for both the provider and the client, helping to manage expectations and improve service quality over time.