In very basic terms the Database Consistency Checker (DBCC) is used to aid in server maintenance. DBCC commands, many of which are completely undocumented, provide a set of commands that let you perform routing maintenance, status and validation checks. The most common DBCC commands are: DBCC CHECKALLOC (Lets you check disk allocation); DBCC OPENTRAN (Lets you check any open transactions); and DBCC HELP (shows a list of available DBCC commands to aid your server maintenance processes).
