Literally ' But Emails ! ' Your man ' s a Russian plant . The election ' s over . Time to face it . It ' s nobody ' s fault but his . And , if you voted for him , 159 m yours . <| sep |> Are you shitting me ? I saw some of the other logs and comments , but these are outrageous . Burn this whole damn site to the ground <| sep |> Extension methods are afaik only a syntactic matter . Before C # 3 , if you wanted to extend upon an unaccessible sealed class , you would have to do something like this public static class MyClassUtil public static void DoSomethingMyClass value actual implementation of Something using value and use MyClassUtil . D oSomethingmyClassInstance . It ' s not really a huge problem to implement extensions this way either . but it spreads the functionality out away from the actual class . With the modern implementation of extensions public static class Extensions public static void DoSomething this MyClass value actual implementation of Something using value you can call upon it through the actual instancemyClassInstance . DoSomething , meaning that although the written implementation is spread out , the actual access to the method is gathered within the class itself . The only difference here really is the first parameter of the method , pointing to this instance , making the method use the instance accessing it the first parameter . TLDR no , Extensions is not a keyword , this within the parameter however is .