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.
should be used when a meta-question is debating whether a question is on-topic or not
Questions about the chat room (Biosphere) & chat functionality, room rules, accepted practices, chat sessions etc.
refers to questions related to the Stack Exchange Community user and the actions that it takes.
Questions about declined flags, or why a specific comment flag was declined.