In C# We cannot use a Keywords as an Identifier since the former is predefined and has special meaning to the compiler whereas an identifier is user-defined. However, we can use a keyword as user-defined identifier by appending “@” (at) or “_” (underscore) characters.
For example: if we write
Class class //Conflict error
It throws an error. Here we can place @ or _(underscore) before class to use it as class name.
Class @class / _class //No error
In the same way we can also write as
@class = 5;
Like this we can use @class or _class as identifier.