What is the use of DBCC commands?

DBCC stands for database consistency checker. We use these commands to check the consistency of the databases, i.e., maintenance, validation task and status checks.
E.g.
DBCC CHECKDB - Ensures that tables in the db and the indexes are correctly linked.DBCC CHECKALLOC - To check that all pages in a db are correctly allocated.DBCC CHECKFILEGROUP - Checks all tables file group for any damage.