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.
For discussions about the site's scope - what questions and topics should and should not be on-topic on the site.
For discussions about the site's tags - what tags we should have (and which ones should be removed), and what topics each tag should or should not include.
for Meta discussions about a specific question on the main site.
Applies to meta questions about "homework"-tagged questions on the main site.
For questions about the /review path where users can view and act on posts by other users that the system thinks may need attention.