A tag is a keyword or label that categorizes your question with other, similar questions. Using the right tags makes it easier for others to find and answer your question.
Questions about what topics are allowed on the SE. What do we want to keep around here and what is considered "off-topic" as it may be better for another SE.
This is the amount that someone can put onto a question to entice others to answer in gaining more reputation. This is for questions around this feature.
Elections are held to choose moderators for Stack Overflow and non-Beta Stack Exchange sites.
Questions flagged as duplicate, and/or reasons to do so.
For questions about the flagging process, how flags are handled, etc.