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 the tools available for users with at least 10000 points of reputation.
the answer the question owner thought best met their needs. Accepting is encouraged but never required. This tag is for *discussing* issues related to accepted answers, not indi…
Questions specifically about the process of asking questions on this site.
For questions about bonus reputation obtained when associating SE accounts.
awarded to encourage and incentivize positive community actions within the site.
should be used when you are expecting a large number of diverse answers to a question.
For questions about the words and phrases which are blocked from appearing in posts or titles.
For discussions about blacklisted tags and proposals to blacklist some tags.
a way to get additional attention for a question by offering some of your own reputation for great answers.
Some changes to questions, such as edits or receiving new answers, will "bump" them back onto the site's front page where the changes can be vetted by other users.
For questions about citation helper feature.
For questions concerning citation of posts from MO and citation of other resources when posting here.
For questions related to closed questions (and on-hold question) and also process of closing in general.
the block of links that appears near the top of the right-hand sidebar on most pages, consisting of featured posts, events, blog entries, and hot meta posts.
For questions about the user named Community ♦ present on MathOverflow (and other Stack Exchange sites.)
A tag for questions about the community wiki feature (regardless of whether or not the questions themselves are community wiki).
For questions about the copyrights of the Stack Exchange sites themselves or about the posting of copyrighted material by users.
Cross posting refers to posting the same, or almost the same, question (or post) on different sites in the Stack Exchange network (or possibly also elsewhere).
The Stack Exchange Data Explorer (SEDE) allows you to create and run queries against copies of the databases of popular Stack Exchange sites.
For questions about user accounts that have been deleted, or the general process of account deletion.
for questions deleted from the site. The tag 'specific-question' should also be used when referencing a specific question that has been deleted.