Besides gaining reputation with your questions and answers, you receive badges for being especially helpful. Badges appear on your profile page, flair, and your posts.
There are three different types:
Bronze
Bronze badges encourage users to try out new features on the site. They are easy to get if you try!
Silver
Silver badges are less common than bronze ones. You'll need to plan your strategy to get one of these.
Gold
Gold badges recognize important contributions from members of the community. They are rarely awarded.