title: What is the purpose of redirect_uri parameter when exchanging code for access token
body: <p>I am reading the Google's documentation about OpenId Connect
  <a href="https://developers.google.com/accounts/docs/OAuth2Login" rel="nofollow">https://developers.google.com/accounts/docs/OAuth2Login</a></p>
  
  <p>What I don't get is the purpose of the redirect_uri parameter during "4. Exchange code for access token and ID token".</p>
  
  <p>The access token is returned in the response to HTTP Post request itself so I don't get the purpose of redirect_uri. </p>
  
  <p>Can somebody explain?</p>