When ever i create a new project, the Fragment_main.xml file is added to my Layout folder and unlike in Eclipse it is this file that contains what is normally in the Activit
If you are creating a new Project and it adds fragment_main.xml by default you must be selecting a layout by default. Maybe a pager/spinner layout?
Fragment_main is the same as activity_main. The names are just string labels and mean nothing in and of itself and are just changed for clarity by the IDE.
Have a read of this.
http://developer.android.com/guide/topics/ui/declaring-layout.html