title: What is the meaning of xmlns:android?
body: <p>Why is everyone use <a href="http://schemas.android.com/apk/res/android" rel="nofollow">http://schemas.android.com/apk/res/android</a> ?
  Do I need sometimes to use something different that this url ?
  Who need this url ?, is something like package I mean what is the point with it</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
      android:orientation="vertical"
  </code></pre>