What is GroupBy meant to do – Simple Explanation

As always we will try to formulate a simple explanation of what is really going on.

Airport Imagine you are at an airport and (as always) there is a queue and planes are delayed. See below. What you will immediately notice is that all of the passengers are grouped together promiscuously – standing around in slumps in no particular order. Every body is mixed up with each other.

But, when you get into the plane, everybody is grouped into three distinct orders:

1. First class
2. Business class
3. Third class. These classes are defined today by folks’ ability to pay. Unlike the olden days. Anyways, let’s move on.

That’s basically what group by does. It takes a promiscuous group and separates them into distinct orders – in this case, three distinct groups of people: first, business and third class.

So now you can say: • Get me all the names of all the people in first class. • Get me the names of all the people in the middle class who live in Europe.

And it’s as simple as that! As for the technicalities: please refer to the MSDN documentation – hopefully reading it won’t cause too much discomfort.