What is database management system in DBMS

DBMS is a collection of program or software that used to create and mantain database. For example: SQL MySql, Orcle etc. 

DBMS provides various operation like database creation, sharing  and access multiple users. 

The database management system is general purpose software system that facilitiate the process defining constructing manupulating and sharing database among various users and application.

Defining a database involve specify the data type, structure and constraint the data to be store in database. constructing the database is the process of storing the data itself on some storing medium of some controling medium.