Answer:   The using keyword has several uses-

1. The using statement defines a scope at the end of which an object will be disposed.
2. The using directive creates an alias for a namespace or imports types defined in other namespaces.
3. The using static directive imports the members of a single class.

Answer:   Using is a convention or a short-cut method which allows us to access the classes in a namespace by referencing it on top of the class. whenever we need to use the classes or methods from the namespace, we can avoid typing the entire namespace hierarchy.