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A service-level agreement or SLA is an accordance between two or more parties where one is the client and other is a service providers. SLA is a segment of a service contract where a service is formally stated. SLA agreement clarifies the level of service quality, availability of service and the procedure of reporting and resolving problems that appear.
The term SLA is sometimes is used to talk about the contracted delivery time- that the services should be provided to the customer as agreed upon in the contract.