How does the Unity Karma and Rank work?

I am fairly new to Unity community and it seems as though they support you to answer questions with karma and badges along with ranks. My question is how does it all come into place with the numbers and dots by usernames? and why does my karma reset?

I would answer this, but it’s already answered, right here on this page to the right. See where it says ‘Welcome to Unity Answers’? And there’s a video tutorial?