Roleplay EXP is awarded to players who make an effort to roleplay using the in-character communication verbs. After typing 5,000 characters IC, that character is awarded experience equal to 10% of their next character level's needed experience, to a minimum of 100 XP per character level. This bonus can be earned once every in-game day (which is roughly 2 hours real-time), but is otherwise not limited. In addition, progress towards this 5,000 character goal is saved over character log-outs, server resets, etc.
Game administration can revoke your ability to gain this bonus if they find you are abusing it (for example, not roleplaying, spamming, etc.).