I have been struggling with why LINQ (Language Integrated Query) was even useful for the last few weeks, and then finally the penny dropped. While I could go into an elaborate explanation of it inner wonders, I would prefer to share with you the source of my epiphany. I stumbled across a great video from Charlie Calvert that includes a interview with Anders Hejlsberg (Chief architect of C#).
At first I was looking into LINQ as a replacement for direct SQL query access, or just another way to write or access XML, however, LINQ is much more. It is a common way to link (pardon the pun) all of the above and more. I was able to really grok the concept as I listened to Anders speak. It really figures to join our various data sources and the programming world in a very intuitive way. It has a very specific nomenclature to describe data relationships much the same way SQL does (select, where, group by, etc).
Disclaimer The opinions expressed herein are my own personal opinions and do not represent my employer's view in any way.