What are active topics?

From Faq.asianfanatics.net

Active topics are topics that just got bumped up because someone just opened it, or someone replied to it.

Another version are Your active topics. These are topics that you made or where you replied in, which are bumped up. If it's a topic that you made (you're the topicstarter), the list will show this in red. Remember though, only topics which are replied (bumped) will be listed. Topics with replies which are edited won't show up.