title: How outdated is “HTTP: The Definitive Guide”?
body: <p>I’m considering buying <em>HTTP: The Definitive Guide</em> with the goal of properly understanding HTTP and related technologies. I’m wondering if—13 years after its publication—the book is still worth buying.</p>
  
  <p>To help me make a decision, I’m looking for input on two questions:</p>
  
  <ol>
  <li><p>What important changes have happened in the world of HTTP that the book doesn’t cover? (For bonus points: what resources are recommended reading to catch up?)</p></li>
  <li><p>Are any of the sections not relevant anymore at all?</p></li>
  </ol>
  
  <p>Check the book’s <a href="http://shop.oreilly.com/product/9781565925090.do" rel="noreferrer">table of contents</a> to get an idea of what’s covered.</p>
  
  <p>Edit: This book isn’t about web fronted technologies. Obviously, there have been dramatic changes in that area since 2002. Please answer with respect to HT<strong>TP</strong>. Thanks.</p>