title: What is android:contentDescription="@string/desc" in ImageView's xml?
body: <p>I added an <code>imageView</code> in <code>GraphicalLayout</code> but it looks different on my real device than on AVD. </p>
  
  <p>I found that I need to add <code>contentDescription</code> in a layout <code>.xml</code>, but when I add: <code>contentDescription="@string/desc"</code> </p>
  
  <p>there is an error:</p>
  
  <blockquote>
    <p>"No resource found that matches the given name (at 'contentDescription' with value '@string/desc')"</p>
  </blockquote>
  
  <p>What is this string "desc"? What should it looks like?</p>