title: Difference between clean project and rebuild project in android studio
body: <p><strong>What is the difference between <code>Clean Project</code> and <code>Rebuild Project</code> (in Android Studio)?</strong></p>
  
  <ul>
  <li>I had a problem with the <code>R file</code> about <code>res</code> <code>ids</code>, so I changed the file extension from <code>gif</code> to <code>png</code> and then [my build failed.]</li>
  <li>I found the solution was to <code>Rebuild Project</code>.  This prompts my question above.</li>
  </ul>