Service level is the quality of a service that is provided. In the IT field, it mainly refers to communication services and application services. That is, in regard to issues such as transmission speed and periods when services are unusable, it is a "level" that expresses whether a user can use a service without any problems.
To improve and preserve service levels, it is necessary for the service receiver and the service provider to agree in advance on things like range and contents of services as well as performance targets. The agreement concerning that service level is called a "service-level agreement" (SLA).
