title: why is there content_main.xml and activity_main.xml by default instead of just activity_main.xml?
body: <p>I have just begun learning Android App development. I have Android Studio 1.4. In my layout folder I have two XML files (<code>content_main.xml</code> and <code>activity_main.xml</code>). I use online tutorials to learn but they have only <code>activity_main.xml</code> in them. So what i want to know is what are the functions that should be used in these respective files. can i just use <code>activity_main.xml</code> and just let the other be ? and vice versa.</p>