A "database management system" (DBMS) is a suite of computer software providing the interface between users and a database or databases. Because they are so closely related, the term "database" when used casually often refers to both a DBMS and the data it manipulates.
Outside the world of professional information technology, the term database is sometimes used casually to refer to any collection of data (perhaps a spreadsheet, maybe even a card index). This article is concerned only with databases where the size and usage requirements necessitate use of a database management system.
The interactions catered for by most existing DBMS fall into four main groups:
Data definition. Defining new data structures for a database, removing data structures from the database, modifying the structure of existing data. Update. Inserting, modifying, and deleting data. Retrieval. Obtaining information either for end-user queries and reports or for processing by applications. Administration. Registering and monitoring users, enforcing data security, monitoring performance, maintaining data integrity, dealing with concurrency control, and recovering information if the system fails.
A DBMS is responsible for maintaining the integrity and security of stored data, and for recovering information if the system fails.
Both a database and its DBMS conform to the principles of a particular database model. "Database system" refers collectively to the database model, database management system, and database.
Physically, database servers are dedicated computers that hold the actual databases and run only the DBMS and related software. Database servers are usually