title: What is the use of # in url
body: <p>I realized that many of web app use <code>#</code> in their app's URL.</p>
  <p>For example, <a href="https://analytics.google.com" rel="nofollow noreferrer">Google Analytics</a>.</p>
  <p>This address is in the URL bar when I am viewing the visitor's language page:</p>
  <pre><code>https://www.google.com/analytics/web/?hl=en#report/visitors-language/a33185827w60383872p61754588/
  </code></pre>
  <p>This address is in the address bar when I am viewing the visitors' geolocation page:</p>
  <pre><code>https://www.google.com/analytics/web/?hl=en#report/visitors-geo/a33185827w60383872p61754588/
  </code></pre>
  <p>I think that this is the Google Analytics web app passing <code>#report/visitors-language</code> and <code>#report/vistiors-geo</code>.</p>
  <p>I know that Google analytics is using an <code>&lt;iframe&gt;</code>. It seems that only the main content box is changing when displaying content.</p>
  <p>Is <code>#</code> used because of the <code>&lt;iframe&gt;</code> functionality?</p>