How to decide between C# static and non-static methods?

Question

[Edit]

My original-question was \"Why to decide between static and non-static? Both do the same...\"

Unfortunately it was edited to a C#-specific question wh

Answer 1

In general if you have method like:

Document.Copy(myDocumentObject, toPath);

I think it is better to use a non-static method, because the first parameter being a Document suggests that it is really an operation on the document.