title: "How are" Android applications (Facebook etc.) installed to an android phone?
body: <p>I know how to install an application to an <code>Android</code> device e.g from <em>Play-Store</em> or via an <em>.apk</em> file. But I'd like to understand the actual process of installation.</p>
  
  <p>E.g. on Windows:</p>
  
  <ul>
  <li>Serial codes etc. are placed in the registry</li>
  <li>Files important to the running of software are placed within the <em>Program Files</em> folder (<em>the main <code>.exe</code> etc.</em>)</li>
  </ul>
  
  <p>So far, what I do know about the <code>Android</code> application installation process is:</p>
  
  <ul>
  <li><p>After an android application has been executed (post-installation), data freshly downloaded is placed in locations like: <em>Android/data</em> or <em>Android/obb</em> etc.</p></li>
  <li><p>If specifically expressed by an Android developer, files can also be placed elsewhere e.g. on <em>secondary storage</em> (memory cards, cloud storage etc.)</p></li>
  </ul>
  
  <p>But other than that, my knowledge concerning the Android installation process is pretty slim e.g.:</p>
  
  <ul>
  <li><p>I don't know where important files relating to an Android program's execution are placed (in the case of Windows, the <em>.exe</em>, related media, libraries etc.)</p></li>
  <li><p>I similarly don't know how these files are structured upon an Android device (post-installation) e.g. are these files structured in folders like: <em>java</em>, <em>res</em>, <em>menu</em>, <em>layout</em> etc. as during development within environments like Android Studio?</p></li>
  <li><p>Neither do I know how what application file-types are stored on a user's device post-installation (after being unpacked from the android installation file or <em>apk</em>) e.g. are they stored as <em>.java</em> and or <em>.xml</em> files, as during development etc.</p></li>
  </ul>
  
  <p>Hopefully someone can fill in the blanks, thank you. </p>