Why would you use Expression> rather than Func?

Question

I understand lambdas and the Func and Action delegates. But expressions stump me.

In what circumstances would you use an Expression

Answer 1

There is a more philosophical explanation about it from Krzysztof Cwalina's book(Framework Design Guidelines: Conventions, Idioms, and Patterns for Reusable .NET Libraries);

Edit for non-image version:

Most times you're going to want Func or Action if all that needs to happen is to run some code. You need Expression when the code needs to be analyzed, serialized, or optimized before it is run. Expression is for thinking about code, Func/Action is for running it.