Badges teach new users how Stack Exchange works and encourages activities that are positive to the community. They are assigned automatically by the system network-wide and questions about them are best asked at Meta SE rather than Meta GIS SE.
Badges are little bits of digital flair made to help teach new users how Stack Exchange works and to encourage activities that are positive to the community. They are assigned automatically by the system.
Stack Exchange badges 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 Geographic Information Systems Stack Exchange. 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 community 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.
Source : help center