Brief explanation of w3wp.exe

I have been asked by sharepoint colleagues what is w3wp.exe. The question is usually asked when they are watching me debug.

w3wp.exe is the worker process for asp.net when using iis 6.0. In iis5.0 the worker process was called aspnet_wp.exe.

A good set of diagrams of the interelation between asp.net and iis 6.0 and iis 5.0 can be found in the screencast web304 - by Rob Howard as part of the heroes happen event.