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 questions regarding tag wikis and excerpts - these little info boxes describing tags that you're reading right now!
for announcements or organisation of events within the community - such as movie or gaming nights, contests and competitions, or other things that people can enter.
questions about this site - Meta Arqade Stack Exchange - should use this tag.
when a user offers a portion of their reputation to be awarded to an answer on a question. They are used to draw in more attention to post. Use this tag for questions you may have about …
Questions about diamond (♦) moderators, their powers, and actions they have taken.
denotes discussion on the subject of game recommendations. The discussion has expanded so large that its own tag became necessary.
for questions about Arqade's (now defunct) gaming blog, available in a read-only fashion here: https://blog.gaming.stackexchange.com/
questions about or addressing the community surrounding Arqade should use this tag.
for questions regarding managing your account on Arqade or the Stack Exchange Network
for questions about the new user experience & how to improve upon it. If you're a new user, try tagging with what it is you are trying to do instead, such as [asking], [answering], [allowed-questions]…
relating to the process of asking a question and answering it yourself - either immediately via the 'Ask Question' page or from finding out the answer yourself later.
if your meta question is regarding Pokemon questions, answers, tags, or moderation efforts regarding the [pokemon] family of tags
Contests run by Gaming.SE to drive site traffic and win phat lewtz.
Indicates that the site developers were not able to replicate the behavior reported.
'deleted' are still visible for users with 10k+ reputation. If your question pertains to one or more deleted questions, and/or the tools surrounding deletion, use this tag
For questions about the handling of unsolicited advertisements posted to the site by automated bots (and sometimes by real people). Anything that deserves a Flag for Spam.
for questions about tags which define subcategories under a game, such as [tf2-spy], [minecraft-commands], or [mass-effect-3-multiplayer]
About the "Mass Effect 3 Missions" contest, where users ask and answer 'mass-effect-3' tagged questions to win ranks and prizes.
if your meta question is regarding Diablo 3 questions, answers, tags, or moderation efforts regarding the [diablo-3] family of tags
questions relating to the image uploading functionality for questions and answers should use this tag.
if one or many similar questions have become obsolete due to a game patch, update, or new version, and you want to discuss what do do with the outdated questions, use this tag
the answer the question owner thought best met their needs. This tag is for discussing issues related to accepted answers, not indicating that a question has an accepted answer.