Describe the evolution from centralized DBMSs to distributed DBMSs.

 A major motivation behind the development of database systems is the desire to integrate the operational data of an organization and to provide controlled access to the data. Although integration and controlled access may imply centralization, this is not the intention. In fact, the development of computer networks promotes a decentralized mode of work. This decentralized approach mirrors the organizational structure of many companies, which are logically distributed into divisions, departments, projects, and so on, and physically distributed into offices, plants, and factories, where each unit maintains its own operational data. The shareability of the data and the efficiency of data access should be improved by the development of a distributed database system that reflects this organizational structure, makes the data in all units accessible, and stores data proximate to the location where it is most frequently used.

Distributed DBMSs should help resolve the islands of information problem. Databases are sometimes regarded as electronic islands that are distinct and generally inaccessible places, like remote islands. This may be a result of geographical separation, incompatible computer architectures, incompatible communication protocols, and so on. Integrating the databases into a logical whole may prevent this way of thinking.