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.
distinguish humans from bots.
"The Dupehammer" refers to the ability of tag gold badge owners to unilaterally close and reopen duplicates which were asked in tags of which they have a golden badge.
For questions related to specific review audits that appear to be faulty or with which you disagree.
When viewing a question, the "Related Questions" block is shown on the right side of the page and provides a system-generated list of questions similar to the current one.
for questions about posts that violate the SE 'Be Nice' policy
Score means the total number of upvotes minus the total number of downvotes.
For questions about timestamps that appear in notices and tooltips upon hovering those notices.
A message displayed to alert the user to a problem or potential problem.
For questions relating to the reputation tab in user profiles.
Indicates a post used for submitting and voting on Community Promotion Ads.
For questions involving the "Ignored Tags" specified in a user's Preferences. Questions with these tags are dimmed or removed entirely from question lists.
For questions about the timeline view of questions, accessible using the clock icon next to the post or via "/posts/xxx/timeline".
For questions about various counters showing number of views of a particular question, profile page, ...
for questions about the 'protected' in 'protected question'
for questions involving issues of how words or names are spelt.
For questions and discussion related to (ab)use of the site in the context of exams.
For questions related to the support of HTTPS by Mathematics Stack Exchange, which is finally live as of spring 2017.
For questions about the 'being nice' behavior we expect from all Stack Exchange users. What this entails can be found in the help center on every site.
Reverts a post to the previous edit version, if any exists.
time within which actions can be revised without a trace in the system. This includes a period in which you can undo and change your vote; a period where editing posts can be done free…
For questions related to the sort orderings of questions, answers, and other lists on SE sites.
Questions that have been closed as duplicates may sometimes be merged by moderators. One question is retained as a stub while all answers appear on the other.
for questions regarding unregistered users.
For questions discussing possibilities to privately contact other users.
For questions on the posting/quality/reviews of late answers.
For questions about vandalism, the deliberate act of damaging a post.
Questions related to "The 7 Essential Meta Questions of Every Beta"
Indicates that the feature request or bug is something that is intended to be implemented or fixed, but not in the near term.