With every post you make or topic you create you earn coins, shown in your profile and on the left side of your posts, underneath your avatar. These coins can be spend in the site’s shop on items for your characters, character changes and second or third characters, as well as school related things like redoing tests or projects. Another thing you can buy is one week to one month of chat box moderation.
Coins can also be earned in other ways, only than posting and creating topics. You can earn coins with being chosen as Student of the Month or Member of the Month, or you can win coins in contests.
Creating topics gives you 3 coins, while posting in already existing topics gives you 1 coins. Posting in the roleplay each time earns you more coins; 5 coins for each roleplay post. When making a minor roleplay yourself, posting in it earns you 0 coins, sadly, while creating a topic yourself earns you 2 coins. This because a minor roleplay might be fun but it doesn't belong to the main and actual roleplay. It's just there for fun.
When becoming Student of the Month (also known as character of the month) you earn 70 coins, same goes for becoming Member of the Month. When winning a contest third place gives you 15 coins, second place 25 coins and first place 50 coins.
You can also earn coins due special ‘giveaways’; once in a while the admin/Headmaster spends his coins on the members who have been online in the last 24 hours or who have been great and active members over the last few days/weeks/months/etc.