A database is a collection of records or data that is stored in a computer system. The structure of a database is dependent on how the data is organized, according to a particular database model. Today we commonly use a relational database model. Other models include a hierarchical model and the network model.
A computer database relies on software to organize the data and how it is stored and retrieved. The type of software used for this is called a database management system (DBMS). Database management systems are categorized according to the database model that they support. The model, in turn, determines the query languages that are available to access the database. This determined how the data is retrieved, manipulated and then used to make business decisions. Other important issues that a DBMS addresses include managing performance, concurrency, integrity, and recovery from hardware failures.