A thread is considered off-topic when the discussions within it deviate from the original idea or discussion for which it was created. This most often occurs in threads where a question is asked and answered within few posts, or in threads with barely any discussion potential (see Abicion Topic). Topics that continue on for very long also tend to digress from the original intent, often to the point of requiring a lock.

There are some posters that try to take threads off-topic as a sadistic sport while others just have brains that don't work properly in a linear context and tend to drift from one subject into another.