title: Why does an anchor tag's href values need http:// preprended to the URL?
body: <pre><code>&lt;a href="www.stackoverflow.com" target="_blank"&gt;click here&lt;/a&gt;
  </code></pre>
  
  <p>Clicking the above link on a site's HTML page would try to take the user to </p>
  
  <pre><code>&lt;site&gt;/index.html/www.stackoverflow.com
  </code></pre>
  
  <p>Where as following works fine</p>
  
  <pre><code>&lt;a href="http://www.stackoverflow.com" target="_blank"&gt;click here&lt;/a&gt;
  </code></pre>
  
  <p>What is the rationale for this behavior?</p>