In Keycloak, a CLIENT refers to an application or service that interacts with the Keycloak server for authentication and authorization purposes.

 Authentication checks credentials like username and password provided by user against stored credentials...

Apache License 2.0  of an open source project is used for corporate use.

The main language of Keycloack source code is

@RoleHierarchy annotation  can reduce the number of @RolesAllowed or @PreAuthorize annotations that you need to write

Spring Security is a framework that focuses on providing authentication, authorization, and protection against common attacks.

Authorization determines that within the application, which task a user is allowed to do.

Authorization is a process of Identifying if the person is allowed to do this operation.

Anybody can view, use, modify an open source project , and contribute to it, depending on the license.

 Users can be individuals who need to access applications or services secured by Keycloak or administrators who manage the Keycloak realm and its configurations.