Is there any technical reason to use or not to use var in C# when the type is known?

Question

It seems that more and more C# code I read uses the var type identifier:

foreach (var itemChange in ItemChanges)
{
   //... 
}

Answer 1

var is a C# 3.x+ feature, isn't it? without using that, your code is more compatible with other versions too.

And there is lots of interesting questions in SO, when you search "var C#"