MyBB Community Forums

How do I add a option for thread prefixes where the user could add a prefix to the thread he is creating. I saw it on another forum and thought it would be a good idea for my forum.

Admin CP>Configuration>Thread Prefixes it's for telling people what might be in the thread.

You may see this wiki page as well to know how to create and style Prefixes:
[Wiki: Admin_CP_Config_Thread_Prefixes] (Broken link, head over to docs.mybb.com instead)