It is a contract between the service provider and the end user. It defines the layout about what services are expected and what services will be provided.The provioder of service provide the services as per the manner mentioned in the service level agreement.
Service Level Agreements can be used between the service provider (internal or external) and the end user .The volume, accuracy, speed, efficiency, vary according to the service level agreement.
Service Level Agreements must contain the description of the service being provided, reliability, responsiveness, procedure for reporting the problems, consequences of not meeting service obligations, monitoring and reporting service level, escape clause or constraints.