Comments are very sought after commodity on Belletristica. Everyone loves receiving comments for their books, and writing comments is a great way to earn a lot of Fairy Dust.
If you especially like or agree with a certain comment, you can applaud to it, which grants an extra dose of Fairy Dust to whoever wrote it.
Leaving comments is also an effective way to get more people to visit your own profile, which helps you reach a bigger audience for your own books.
When an author is really happy about a comment, they can choose to pin it to the top of the comment list for everyone to see.