Getting started with Lamba Expressions

C# 3.0 brought so much news (for example var, extensions ,LINQ, lambda expressions etc...).
Sometime companies have its reason to don't update .NET framework in their applications.
For this, developers who grow parallely to those applications, never have time to upgrade their knowledges.

I know companies that use 2003's IDE in 2011!

For those who never had a chance to see what's new in latest framework, like me, I dedicate this post.

What is a lambda expression and what can I do with it?

It's "an anonymous function that can contain expressions and statements, and can be used to create delegates or expression tree types" (msdn).