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

First bounty you manually award on another person's question
First bounty you manually award on your own question
Ask a good question on 5 separate days, and maintain a positive question record
18 awarded
First bounty you offer on another person's question
Question score of 10 or more
67 awarded
Question with 1,000 views
4 awarded
First bounty you offer on your own question
Ask a question and accept an answer
105 awarded
First question with score of 1 or more
160 awarded
Asked a question with zero score, no answers, no comments, and low views for a week
4 awarded

Answer Badges

Edit and answer 1 question (both actions within 12 hours, answer score > 0)
7 awarded
Answer score of 10 or more
83 awarded
Answer more than 30 days after a question was asked as first answer scoring 2 or more
10 awarded
Answer your own question with score of 3 or more
14 awarded
Answer a question with score of 1 or more
171 awarded

Participation Badges

Complete "About Me" section of user profile
2.4k awarded
Leave 10 comments
56 awarded
Earn at least 200 reputation (the daily maximum) in a single day
Followed the Area 51 proposal for this site before it entered the commitment phase
Post 10 messages, with 1 or more starred, in chat

Tag Badges

You must have a total score of 100 in at least 20 non-community wiki answers to achieve this badge.
9 awarded

Moderation Badges

First flagged post
14 awarded
First rollback
6 awarded
First down vote
110 awarded
Complete at least one review task. This badge is awarded once per review type
4 awarded
Delete own post with score of 3 or higher
3 awarded
First edit
111 awarded
Edit first post that was inactive for 6 months
2 awarded
First retag
28 awarded
Delete own post with score of -3 or lower
3 awarded
Approve or reject 100 suggested edits
Use 30 votes in a day
3 awarded
First up vote
640 awarded
First approved tag synonym
1 awarded
First tag wiki edit
2 awarded
Use the maximum 40 votes in a day
3 awarded

Other Badges

Visited every section of the FAQ (retired)
54 awarded
Share a link to a question later visited by 25 unique IP addresses
2 awarded