A database is a system intended to organize, store, and retrieve large amounts of data easily. It consists of an organized collection of data for one or more uses, typically in digital form. One way of classifying databases involves the type of their contents, for example: bibliographic, document-text, statistical. Digital databases are managed using database management systems, which store database contents, allowing data creation and maintenance, search and other issues related to access.

A database management system (also known as DBMS) is maintained by the software which operates database and provides facility to store, search, access, backup and other facilities. DBMS can be categorized into two major categories— Rational database management system (RDBMS) and Object database management system (ODBMS) according to the database model which they support like XML, MySQL, SQL Server, Microsoft Access, Oracle, Sybase, FoxPro, etc. Almost all the database software comes with inbuilt Open Database Connectivity (or ODBC) driver which allow the database to connect and integrate with other database.

Both types of database management systems have separate components to manage the database. RDBMS components are sublanguages, interface drivers, SQL engine, Transaction engine, storage engine and relational engine while the ODBMS components has transaction and storage components to handle the database.

Database also can be categories in many categories according to the type of database like:

Operational database: stores detailed data related to the operations of an organization. These are prepared to maintain the overall or specific records of the organization like library books record, employee’s salary record, etc.

Data warehouse: is used to rearrange and classify the data received from external sources so that the primary and secondary data can be used efficiently.

Analytical database: is prepared by the data warehouse and provides the finalized database.

End-user database: keeps the data developed by the individual end-users like word processing files and spreadsheets.

Hypermedia database: This database is maintained over the web where web crawlers and other software collects and analysis the data to support search engines.