Apologies for what may very well be a stupid question.

I'm just intrigued as to (a) will indexing improve performance (b) how will it improve performance and (c) why will it improve performance?

Also, if this does improve performance, would this be the case across the board for LINQ to SQL, LINQ to Entities, LINQ to Objects, etc, etc. 

Again, if this is a really stupid question, I do apologise.