Web API and OWIN

I'm new to web api and owin, and still don't understand it. I want to create a server side with it and I would like to get explenation about :

  • how does web api can be used as server?
  • how web api is RESTful service?
  • what does it mean web api self host?
  • why do I need owin?
  • what is the difference between web api with asp.net vs owin?
  • what is the difference between owin to iis?
  • who creates the other? web api creates owin or the opposite?
  • simple example for web api and owin with explenation.