Dynamic Management Views (DMV) and Dynamic Management Functions (DMF) return server state information that can be used to monitor the health of a server instance, diagnose problems, and tune performance. They can exactly tell what is going on with SQL Server and its objects at the moment.There are tow kinds of DMVs and DMFs. Server-scoped dynamic management views and functions. Database-scoped dynamic management views and functions. All dynamic management views and functions exist in the sys schema and follow this naming convention dm_*. When you use a dynamic management view or function, you must prefix the name of the view or function by using the sys schema.
Following are major categories of DMVs and DMVs.