How extension methods are implemented internally

Question

How are extension methods implemented internally? I mean what happens when the compiler sees a declaration for an extension method and what happens at runtime when there is a call to an extension method.

Is reflection involved? Or when you have an extension method is its code injected in the target class type metadata with some additional flags noting that this is an extension method and then the CLR knows how to handle that?

So in general, what happens under the hood?

Answer 1

extension methods are converted to static functions.In other words,They are syntactic sugar for static functions.