# Multiple-client features available in Derby

Derby contains some features that are useful for developing multi-user applications.

- Row-level locking
  To support multi-user access, Derby uses row-level locking.
- Multiple concurrency levels
  Derby supports the SERIALIZABLE (RR), REPEATABLE (RS), READ COMMITTED (CS), and READ UNCOMMITTED (UR) isolation levels.
- Multi-connection and multi-threading
  Derby allows multiple simultaneous connections to a database, even in embedded mode.
- Administrative tools
  Derby provides some tools and features to assist database administrators, including the following.

Parent topic: Derby in a server framework
Related concepts
Connectivity configurations
The Derby Network Server
Embedded servers
How to start an embedded server from an application
Related reference
Embedded server example