title: What libraries get sent to Android device when running from Eclipse
body: <p>Some things about developing Android apps in Eclipse are not clear. Here are some questions:</p>
  
  <ol>
  <li>I installed Eclipse Kepler along with the Android ADT and created a dummy app. I noticed an app under Package Explorer, called appcompat_v7, is being used by my dummy app. I used a previous version of Eclipse and the ADT and this app was never present. Why now and what's it used for?</li>
  <li>In Eclipse when I select Build Path > Configure Build Path > Order &amp; Export, I notice some items checked off while others are not. I was under the assumption that by "Export", it means that the library will be sent to the device. But even if I uncheck some items and run my app, my app runs anyway without those items checked. So what exactly is Order &amp; Export used for?</li>
  <li>In some of my projects, I have an android-support-v4.jar file. What exactly is this? My assumption is that it has features possibly not found in the core android library that I have selected for deployment. But does this library actually get sent to my device? After all, if my device is running Android 4.1 but my app is set for 4.0, wouldn't all those features in the android-support-v4.jar file already be on my device, meaning that they wouldn't get sent?</li>
  <li>In general, it just isn't clear what libraries get sent to my device when I deploy the app. Is there some easy consistent way of determining what libraries get sent?</li>
  </ol>