title: Difference between golang.org packages and the standard library
body: <p>I've been using go for a short time now, and I've been noticing that there are duplicate packages between Go (standard library) and golang.org/x/.</p>
  
  <p>My questions are: Why are they released twice? And of the two, which one should I use (more up-to-date, canonical, etc)?</p>
  
  <p>Some sample packages that are released twice that I've noticed so far:</p>
  
  <ul>
  <li><code>golang.org/x/net/html</code> vs <code>net/html</code></li>
  <li><code>golang.org/x/crypto</code> vs <code>crypto</code></li>
  <li>and maybe more that I can't remember right now...</li>
  </ul>