Board Thread:Dragon City Gameplay Questions & Answers/@comment-24724301-20140323070348/@comment-10090661-20140323235209

The Stars indicate their ranks. The more Dragons they defeat the higher their rank. With higher rank comes greater HP @ constitution. It also means greater damage. The starting HP of the Dragon depends on the Dragon category assigned to it, a number between 1 and 5. The higher the category the greater starting HP. There's lots more to know of course, but the Ranks are an advantage in Battles because your opponents never have ranks. The highest rank is 3 Gold Stars, which increases the Dragons HP by 50%