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

Ask a well-received question on 100 separate days, and maintain a positive question record
4 awarded
Question saved by 100 users
1 awarded
Question score of 100 or more
5 awarded
Question with 10,000 views
429 awarded

Answer Badges

Edit and answer 500 questions (both actions within 12 hours, answer score > 0)
Answer saved by 100 users
Answer score of 20 or more to a question score of -3 or less that goes on to receive a score of 3 or more
Answer score of 100 or more
12 awarded
Highest scoring answer that outscored an accepted answer with score of more than 10 by more than 2x
38 awarded
Zero score accepted answers: more than 10 and 25% of total

Participation Badges

Visit the site each day for 100 consecutive days. (Days are counted in UTC.)
106 awarded
Earn 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.
7 awarded

Moderation Badges

Raise 500 helpful flags
Served as a pro-tem moderator for at least 1 year or through site graduation
9 awarded
Served as an elected moderator for at least 1 year
5 awarded
Complete at least 1,000 review tasks. This badge is awarded multiple times per review type
1 awarded
Edit 500 posts (excluding own or deleted posts and tag edits)
3 awarded
Vote on 600 questions and 25% or more of total votes are on questions
17 awarded

Other Badges

Share a link to a post later visited by 1000 unique IP addresses
3 awarded

Retired Badges

Provide an answer of +20 score to a question of -5 score