Chapters are the used divisions of the many posts in the Avataria roleplays. At every fifth post, a new chapter starts, and every fifth chapter renews all roleplayers' rights to create one additional secondary character. The chapters are most commonly written in roman numerals, and are always placed above the post counter.
Amargaard revealed in a blog post of his, that he plans to change the chapter system a little in Avataria #3. In Avataria #3 there will be much less chapters, with a lot more distance between them, but instead they will all reset the roleplayers' rights to create an additional secondary character.