Part 42 C# Interfaces 2

What are interfaces,
Why we use it,
The members interfaces have,
How to create object of interface,
access specifiers relation with them,
Inheritance relation with interfaces,
How to create function in interface,
why we create function in interface,
what is the mean of undefine function in interface,
Expilicitly call interface,
if two interfaces have same name function how to implement them,