title: How to reuse Activities? Not to create activity each time
body: <p>This topic is continue of this:
  <a href="https://stackoverflow.com/questions/7674477/">Android. How to start activity without creating new one?</a></p>
  
  <p>I have read that activities are destroyed when to click BACK button.
  They can be not destroyed when to move deeper to stack and then call activities back. using <code>android:launchMode="singleTask"</code> for example</p>
  
  <p>is it possible that activities to not be destroyed when I click button BACK and then run activity again?</p>