In this video, I tried to explain in details what an API is? How does it relate to web service? How does it relate to REST? I also explain REST (REpresentational State Transfer). I explain how the concept relates to the WEB and to HTTP. After that I talked about How RESTful APIs work with diagram and code. Finally, I give a short list of what you need to know to start building APIs. I know the video is sort of long, but I think it is worth your time. I hope there was a video like this when I first wanted to learn about API and REST. And this is probably why I created it. I know the pain, and I don't want you to go through it. Enjoy! :)