What is use of DBCC Commands?

The Transact-SQL programming language provides DBCC statements that act as Database Console Commands for SQL Server.  DBCC commands are used to perform following tasks.

Maintenance tasks on database, index, or filegroup.
Tasks that gather and display various types of information.
Validation operations on a database, table, index, catalog, filegroup, or allocation of database pages.
Miscellaneous tasks such as enabling trace flags or removing a DLL from memory.