title: How does Node.js handle simultaneous requests with one thread?
body: <p>I did some search on the question, but it seems like people only emphasize on Non-blocking IO.</p>
  
  <p>Let's say if I just have a very simple application to respond "Hello World" text to the client, it still needs time to finish the execution, no matter how quick it is. What if there are two request coming in at exactly the same time, how does Node.js make sure both requests will be processed with one thread?</p>
  
  <p>I read the blog <a href="http://blog.mixu.net/2011/02/01/understanding-the-node-js-event-loop/" rel="noreferrer">Understanding the node.js event loop</a> which says "Of course, on the backend, there are threads and processes for DB access and process execution". That statement is regarding IO, but I also wonder if there is separate thread to handle the request queue. If that's the case, can I say that the Node.js single thread concept only applies to the developers who build applications on Node.js, but Node.js is actually running on multi-threads behind the scene?</p>