The SQL Server activity monitor is a utility for getting insight into the performance of your SQL Server. It gives analysis on what the resources are used, which expensive queries may be running and, what memory and resources are taken etc.
Open the SQL Server Management Studio.
Right-click the SQL Server Engine and select "Activity Monitor".
A dialog will open as follows:
In this dialog there are multiple sections
Now click the Process:
See here you will get the Session id, Database, Task State, Wait time etc information. You can change the resource by clicking the dropdown also.
See here you will get all the information of time for the resources are waiting.
Clicking on Data File I/O:
Here you will get all the database names of your SQL Server and the time for data interaction of each database.
Now click on "Recent Expensive Queries".
You will get the entire query that takes the most time to execute or that takes the most resources. You will get the information of the query execution.
Conclusion: In this article I have described how to use an Activity Monitor in SQL Server Management Studio. This process is useful when a web site interacts with SQL Server and you will see what types of resources are taken.