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 30 separate days, and maintained a positive question record
1 awarded
Question favorited by 25 users
Question score of 25 or more
79 awarded
Asked a question with 2,500 views
3 awarded

Answer Badges

First to answer and accepted with score of 10 or more
144 awarded
Edited and answered 50 questions (both actions within 12 hours, answer score > 0)
Provided non-wiki answers of 15 total score in 20 of top 40 tags
Accepted answer and score of 40 or more
9 awarded
Answer score of 25 or more
75 awarded
Answered a question more than 60 days later with score of 5 or more
200 awarded
Zero score accepted answers: more than 5 and 20% of total

Participation Badges

Left 10 comments with score of 5 or more
11 awarded
Visited the site each day for 30 consecutive days. (Days are counted in UTC.)
64 awarded
Earned 200 daily reputation 50 times
Actively participated in the private beta
Posted 10 messages in chat that were starred by 10 different users
Active member for a year, earning at least 200 reputation
6.4k awarded

Tag Badges

You must have a total score of 400 in at least 80 non-community wiki answers to achieve this badge.
2 awarded

Moderation Badges

Raised 80 helpful flags
4 awarded
Voted 300 or more times
25 awarded
Completed at least 250 review tasks. This badge is awarded once per review type
Edited 80 posts
1 awarded
Edited 100 posts that were inactive for 6 months
Up voted 100 answers on questions where an answer of yours has a positive score
Edited 50 tag wikis
Created a tag used by 50 questions
9 awarded

Other Badges

Shared a link to a question that was visited by 300 unique IP addresses