From Online Manual
Topics (often called threads) are collections of messages grouped together under a common title, intended to reflect a single topic of discussion. Topics may have polls and/or calendar events attached to them.
The original poster (also known as the OP) is the member who opened the topic, making the first post in the topic. Sometimes, an administrator may give elevated permissions to the member who started the topic.
Topics can have the following states:
- Sticky - This state indicates that a topic contains important information, or information that may be useful to the subject of the board.
- Locked - This state locks the topic down so only privileged people can reply to it. Common uses for this state are indicating that a discussion is unwanted, or that a conclusion has been made out of a discussion.
The default cap of topics in SMF is 16,777,216 topics.