title: Android XML layout files and namespace
body: <p>Android layouts are defined in XML with this namespace declared in the root element: </p>
  
  <pre><code>xmlns:android="http://schemas.android.com/apk/res/android"
  </code></pre>
  
  <p>Example of an element:</p>
  
  <pre><code>&lt;TextView android:layout_width="fill_parent" android:layout_height="wrap_content" /&gt;
  </code></pre>
  
  <ol>
  <li>Why is the <code>android</code> prefix used instead of ommitting it like <code>xmlns="http...</code> ?</li>
  <li>Why is the prefix used only in attributes and not in elements?</li>
  </ol>