Q:

When/why would you use Linq in an application?

i know how linq works but i am not getting idea where exactly i should use linq? 

A:

The question is rather like asking "I know how plus and minus work, but when do I use addition? When do I use subtraction?"  
You use addition when you want to know the sum of two things and subtraction when you want to know their difference.  
Essentially all LINQ does is add operators to the C# and VB languages for sorting, filtering, projecting, joining and grouping. When do you use LINQ? When you want to sort, filter, project, join or group something. 

A:

I say use LINQ.. Absolutely anywhere that it will help accomplish your goal in a concise and maintainable way.
There is no broad use or don't use restrictions, you really have to make a judgement for the piece of code at hand to whether or not it will benefit from LINQ, in general some of the old overly verbose pieces of code (nested looping etc) can be more clearly expressed in LINQ and might be beneficial.
And it should be noted that LINQ is NOT synonymous with LINQ to SQL, LINQ stands for Language Integrated Query and is extraordinarily useful outside a database context.

