cation or spread over the interconnected network. It is a loosely coupled system. *Shared nothing architecture is used in distributed databases. The concept of distributed database was built with a goal to improve: Reliability: In distributed database system, if one system fails down or stops working for some time another system can complete the task. Availability: In distributed database system reliability can be achieved even if sever fails down. Another system is available to serve the client request. Performance: Performance can be achieved by distributing database over different locations. So the databases are available to every location which is easy to maintain *Heterogeneous distributed database system.