title: Are android apps backwards compatible?
body: <p>Should I build an app that targets Android 2.2 and release it on the Android Marketplace;</p>
  
  <p>Would the app be available for download and use on devices running a version of Android OS lower than the targeted version of the app? - Let's say Android OS version 1.6.</p>
  
  <p>What would happen if a user (with an Android OS version 1.6 powered device) were to attempt to run the app?</p>
  
  <p>Would they be prompted to update their OS or just receive an error message?</p>