I can't understand the concept and, first of all, where it belongs. Is it solely a Shrepoint concept or more general like of ASP.NET or IIS level? Does it only affect authentication and if so how does it affect it? Or what effect does it have on an application? I know it is a broad question, but I've googled for about 15 minutes and haven't been able to find the answer. And it is kind a not so critical for me now but I'm curious.
Can you please give a link to a resource with an explanation of this? Thanks!