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.

Question Badges

Asked a well-received question on 100 separate days, and maintained a positive question record
3 awarded
Question favorited by 100 users
Question score of 100 or more
Asked a question with 10,000 views
15 awarded

Answer Badges

Edited and answered 500 questions (both actions within 12 hours, answer score > 0)
Answer score of 100 or more
Highest scoring answer that outscored an accepted answer with score of more than 10 by more than 2x
Provided answer of +20 score to a question of -5 score
Zero score accepted answers: more than 10 and 25% of total

Participation Badges

Visited the site each day for 100 consecutive days. (Days are counted in UTC.)
40 awarded
Earned 200 daily reputation 150 times

Tag Badges

You must have a total score of 1000 in at least 200 non-community wiki answers to achieve this badge.

Moderation Badges

Raised 500 helpful flags
1 awarded
Served as a pro-tem moderator for at least 1 year or through site graduation
5 awarded
Served as an elected moderator for at least 1 year
Completed at least 1,000 review tasks. This badge is awarded once per review type
Edited 500 posts (excluding own or deleted posts and tag edits)
1 awarded
Voted on 600 questions and 25% or more of total votes are on questions
15 awarded

Other Badges

Shared a link to a question that was visited by 1000 unique IP addresses