This is where you need to debug an application in visual studio, but the process is running on some other machine (i.e. not on your local box). A good example is when a tester is running something and you want to connect to their box to debug it.
This in fact turned out to be a pretty painless process.
First on the machine where the app is running that you need to debug you need to run msvsmon.exe . I found this in
Program Files\Microsoft Visual Studio 9.0\Common7\IDE\Remote Debugger\x86 .
This will bring up the "Visual Studio Remote Debugging Monitor".
More than likely you will be debugging a machine on your network. So goto Tools>Permissions, and add the user of the machine where visual studio is running.
Now run the application you intened to debug
Now in Visual Studio goto Debug>Attach to Process . In the box "Qualifier" , enter the machine name of where your application is running and hit enter.
A list of processes will appear in the "Available Processes" box below. On the other machine in the remote debugging monitor you will see a log that you have connected.
Select the process which corresponds to the app you want to debug from Available processes and click on attach. And that's it you are now in debug mode and you can set your breakpoints and whatever and debug your app in the usual way!
For more info look at this article from microsoft :