Describe in brief system database.

Master Database
Master database is system database. It contains information about server’s configuration. It is a very important database and important to backup Master database. Without Master database, server can't be started.

MSDB Database
It stores information related to database backups, DTS packages, Replication, SQL Agent information, SQL Server jobs.

TEMPDB Database
It stores temporary objects like temporary tables and temporary stored procedure.

Model Database
It is a template database used in the creation of new database.