A database (abbreviated DB) is an entity in which data can be stored in a structured manner, with as little redundancy as possible. Different programs and different users must be able to use this data. Therefore, the concept of a database is generally linked to that of a network used for sharing this information, hence the term base. "Information system" is the general term used for the overarching structure which includes all data-sharing mechanisms that have been installed.
A database gives users access to data, which they can view, enter, or update, within the limits of the access rights granted to them. Databases become all the more useful as the amount of data stored continues to grow.
A database can be local, meaning that it can be used on one machine by one user only, or it can be distributed, meaning that the information is stored on remote machines and can be accessed over a network.
Early on, the need for a management system in order to control both data and users quickly arose. Database management is done using a system called a DBMS (Database management system). The DBMS is a suite of services (software applications) for managing databases, which involves:
The DBMS can be broken down into three subsystems:
The main database management systems are: