Available on Free, Basic, Business
Badges are little bits of digital flair that you earn for almost every kind of activity. The number and type of badges you've earned are displayed together with your name and reputation score around your team as part of your user card.
The badge system exists for two reasons...
Teach new users how the team works.
Encourage activities that are positive to the team effort.
...and fall into three broad categories.
Bronze badges are awarded for basic use of the site; they encourage people to use all the typical, routine functions of the site: posting questions, answering questions, voting up or down, tagging posts, editing, filling out your user profile, and so forth. Bronze badges are relatively easy to get.
Silver badges are for experienced users who regularly use the site. They encourage continued participation and returning to the site by awarding longer term goals. Silver badges are more uncommon than bronze badges, but attainable if you're dedicated.
Gold badges are for the most committed users. They reward the most difficult feats; you’ll have to not only participate in the team but be skilled, knowledgeable, and dedicated to earn these.
Many badges can be awarded multiple times, so don't stop after you've earned a badge once. Badges are always earned by achieving a measurable numeric goal based on data, rather than being arbitrarily awarded by a human. You don’t have to worry about building favor to earn badges; just use the site like you normally would, and the site itself will bestow these badges upon you. That said, badges are supposed to be fun, too!