title: What's a redirect URI? how does it apply to iOS app for OAuth2.0?
body: <p>Beginner programmer here, please pardon ignorance &amp; explanations will be really nice :)</p>
  
  <p>I've tried to read the tutorials for a certain OAuth 2.0 service, but I don't understand this redirect URI... in my particular context, let's say I'm trying to build an iPhone app that uses OAuth 2.0 for some service. I have an App ID that was generated, but i need to provide some sort of redirect URI to generate the API key. </p>
  
  <p>Is this a URL that I'm supposed to host somewhere myself?? As the name suggests, I would think that the redirect URL is supposed to "redirect" someone somewhere. My only guess is that it's the URL a user is redirected to after they log in to the service.</p>
  
  <p>However, even if that assumption is correct, I don't understand one other thing - how can my app be opened again after I've sent them to the browser for the user login?</p>