The badges beneath a user's avatar usually denote what their posting rank is. As your post number increases, so does your badge, and while for the most part these are only decorative signs of your posting activity, some badges actually act as benchmarks to access some other sections of the forums:. This handy guide, made by the user Rikifive, should prove useful to get an understanding of how our badge system works:
MLPF Art Contest Winner: Win an MLPF Art Contest!
Christmas Donor: Donate to the MLPF MCM Fundraiser!
Librarian - Fanfic Readers
Head Librarian - Golden Oaks Team Leader
Stage Pony - Event Coordinators
Wonderbolt - Sectional Staff
Royal Guard - Moderators
Alicorn - Administrators