What does it mean for a question to be closed?
When a question is closed, no additional answers may be posted to it, although the question and existing answers can still be edited (by users with edit privileges or by suggested edits) and voted upon, and will continue to count for badges. The asker of a closed question may still accept an answer.
Closed questions can be re-opened by users who have sufficient reputation.
What does it mean for a question to be marked as a duplicate?
This is just a "special" reason for closing a question. There are no functional differences between duplicate questions and questions closed for other reasons. The only exception is that the question author and users who hold a gold badge for one of the question's tags can bindingly close a question as a duplicate under certain cases.
For more information on the duplicate close reason itself, see How should duplicate questions be handled?.
Who can close a question?
- Users with at least 250 rep may vote to close their own questions
- Users with at least 3,000 (500 on beta sites) may vote to close any questions (see limits below)
- Moderators may close any question (regardless of their reputation) with a single vote
- Users who hold a gold badge for one of the question's tags may close as duplicate with a single vote, within limits that prevent gaming the system
- If there are pending votes or flags to close a question as a duplicate of a certain target question, the question owner can indirectly bindingly close the question as a duplicate of that target (the Community user will cast the actual vote)
- The same users who can vote to close questions can also vote to reopen them
- Users can also retract/cancel their close vote by clicking the close button again and clicking the "Retract Vote" button (you can't cast a close vote again on that question).
What are the limits for closing questions?
- Each user with vote to close privileges gets 24 votes to close per day (50 on Stack Overflow)
- Five votes are required to close or reopen on most sites
- Votes will expire if the question does not reach the required threshold
- Questions with an open bounty cannot be closed (if a bounty question blatantly violates the site rules, flag for a moderator to clear the bounty)
- You can only vote to close once per question, unless your vote expired1
- You can only vote to reopen once per question, unless your vote expired1
- You may not vote to close as duplicate if the other question is marked as a duplicate of the first
- On non-meta sites, you may not vote to close as duplicate of a question with no upvoted or accepted answers, unless you are a moderator or the target question was posted by the same user
- Pending votes to close question A as a duplicate of B expire if B is closed as a duplicate of A
- Pending votes to migrate a question expire once the question becomes 60 days old (and thus ineligible for migration)
What if I don't have enough reputation to cast close votes, but believe a question should be closed?
If you have enough reputation to flag posts, you can cast a recommend closure flag by clicking "flag"..."needs improvement". This will bring up a dialog very similar to the close dialog, and will allow you to choose any close reason except for custom off-topic. (In lieu of that option, you can choose "blatantly off-topic" instead.)
Recommend closure flags do not count towards a question's close votes; your name will not be shown in the notice as it only includes those who cast actual close votes. When you cast a recommend closure flag, the question will be pushed into a review queue where users who can vote to close may cast close votes. As soon as one user agrees with you and votes to close the question, your flag will be marked "helpful". If three users disagree that the question should be closed (without a single user agreeing), it will be marked "declined".
You are subject to the same restrictions when casting recommend closure flags as close votes. Also, if you flag to close as duplicate, an automatic comment will be posted under your name with a link to the target if no one else suggested it, and the same prompt will be shown to the question author (with a link to the target, and an option to close it themselves).
What are the reasons for closing a question?
When closing a question, a reason must be provided for the action. Not all close reasons are available on all sites. If none of the reasons for closing the question apply, you should probably not vote to close.
Questions in these categories may be closed:
Duplicate: Questions that have already been asked and answered in the past should be closed. These serve as signposts to their previously answered duplicates. See How should duplicate questions be handled?
Community-specific reasons: Questions are expected to be within the scope defined by the community.
This option provides further guidance to the author. Closers can either select a predefined message which will show in the close reason box to the author and users with close voting privileges, or type in a custom explanation which will be posted as a comment.
The former "off-topic" option has been renamed to this option.
- Migration (belongs on [another site]): Questions that are off-topic on the site posted, but on-topic on another site in the Stack Exchange network. See What is migration and how does it work?. This close reason can only be picked within 60 days of the question being asked.
Needs detail or clarity: The way the question is currently written, it's hard to tell exactly what is being asked. The explanations in the question are not clear, or it is not clear what kind of answer is expected, or there is not enough information to solve the problem. The question may be reopened if it is clarified or if the missing information is provided.
Needs more focus: The question must be edited to limit it to a specific problem with enough detail to identify an adequate answer, and not ask multiple distinct questions at once.
Opinion-based: While many good questions generate some degree of opinion based on expert experience, answers to this question will tend to be almost entirely based on opinions, rather than facts, references, or specific expertise.
Is closure the end of the road for a question?
Definitely not. Closed questions can and should be edited to improve them and address the reasons why they were closed in the first place. If you edit the question within five days of closure, it will be put into a queue for potential reopening. If you don't get around to editing it within five days, or others don't vote to reopen it in the queue, you should raise a question on the per-site meta to bring it to everyone's attention so it can get more views that might translate into reopen votes. See How do you reopen a closed question?
It's only when a question can't be salvaged that it should move onto the next state - deletion.
When are closed questions eligible for deletion?
Closed questions should only be deleted if they can't be salvaged or they have no lasting value to the site, including their answers. Be wary of deleting duplicates, as those are often used as signposts for searchability purposes.
Users with the moderator tools privilege (10k+ on designed sites and 2k+ on beta and non-designed sites) can vote to delete closed questions 48 hours after they are closed. Additionally, users with the trusted user privilege (20k+ on designed sites and 4k+ on beta and non-designed sites) can vote to delete closed questions scoring -3 or lower within 48 hours of their being closed. See here for the rules governing question deletion. See also Do closed questions ever get deleted?
The Community user automatically deletes closed questions in certain cases.
I saw someone posting an answer to a question after it got closed.
The moment a question gets closed, only the GUI on the main site will prevent answering it. The server does not actually block answers to closed questions until 4 hours after it was closed, to prevent people from losing their work if the question gets closed while they're submitting an answer.
There are cases where the GUI limitation does not kick in, in which you may see users posting answers to closed questions after they get closed (but within four hours of closure):
- They submitted the answer at the same time as the question got closed
- They briefly lost their Internet connection while the question got closed (so they didn't receive the ping that triggers the GUI restriction)
- They posted through the mobile site, mobile app, or the API, which lack a client-side restriction
1 If you cast a close or reopen vote before the status of aged close votes began to be tracked in early 2012, you cannot recast your vote.