title: What is the point of the Access-Control-Allow-Origin http header?
body: <p>I have difficulties in seeing the point of the Access-Control-Allow-Origin http header.</p>
  
  <p>I thought that if a client (browser) gets a "no" from a server once, than it will not send any further requests. But chrome and firefox keep sending requests. </p>
  
  <p>Could anyone tell me a real life example where a header like this makes sense?</p>
  
  <p>thanks!</p>