is that they should be able to receive, maintain, and complete every single request that the main system must perform by themselves. There is only one database file, kept at a single location on a given network. A distributed database, however, is a database in which all the information is stored on multiple physical locations. Distributed databases are divided into two groups: homogeneous and heterogeneous. It relies on replication and duplication within its multiple sub-databases in order to maintain its records up to date. It is composed of multiple database files, all controlled by a central DBMS. The main differences between centralized and distributed databases arise due to their respective basic characteristics. Differences include but are not limited to: Centralized databases store data on a single CPU bound to a single certain physical/geographical location. Distributed databases, however, rely on a central DBMS which manages all its different storage devices remotely, as it is not necessary for them to be kept in the same physical and/or geographical location. As outlined above, centralized databases are easier to maintain up to date than distributed databases. This is so because distributed databases require additional (often manual) work to keep the data stored relevant, and to avoid data redundancy, as well as to improve the overall performance. If data is lost in a centralized system, retrieving it would be much harder. If, however, data is lost in a distributed system, retrieving it would be very easy, because there is always a copy of the data in a different location of the database. Designing a centralized database is generally much less complex than designing a distributed database, as distributed database systems are based on a hierarchical structure. See also Database Distributed database Parallel database Centralized computing Centralization References Types of databases