WebLogic Server uses a mechanism to provide a secure environment, as follows:
A security realm is a mechanism for protecting Oracle WebLogic Server resources, such as Authenticators, Adjudicators, Authorizers, Auditors, Role mappers, and Credential mappers. Resources in a domain are protected only under one security realm and by a single security policy in that security realm. A user must be defined in a security realm in order to access any resources belonging to that realm. When a user attempts to access a particular resource, WebLogic Server tries to authenticate the user and then authorize the user action by checking the access privileges that are assigned to the user in the relevant realm.
In the previous screenshot you can see the different components belonging to a security realm.