To manage workloads or a group of applications, you can define services that you assign to a particular application or to a subset of an application's operations. You can also group work by type under services. For example, online users can use one service, while batch processing can use another and reporting can use yet another service to connect to the database.
Oracle recommends that all users who share a service have the same service level requirements. You can define specific characteristics for services and each service can represent a separate unit of work. There are many options that you can take advantage of when using services. Although you do not have to implement these options, using them helps optimize application performance.