What does it mean for a question to be protected?
Protected questions have the additional restriction that new users are not permitted to answer the question. Unlike locked questions, they can still be edited, commented on, and voted on. You can even vote to close them.
Protected questions have a banner displayed on the top of them, labeling them as a "highly active" question. This banner changes depending on whether or not the viewer has enough reputation to answer protected questions.
Why are some questions protected?
Questions are usually protected because they have attracted either spam answers or "noisy" answers such as "thank you", "this worked for me", or "I'm also having this problem" from new users who may mistake the site as a traditional forum.
Who can protect and unprotect questions?
- Diamond moderators can protect and unprotect any question, regardless of age or answer history.
- Users with the Protect Questions privilege (15k reputation on graduated sites, 3.5k on beta sites)
- The system (via the Community user) will automatically protect questions if a certain number of answers from new users get deleted or are posted within a short time. See When does the Community user protect a question? below for more info.
Who can answer a protected question?
Users with 10 or more reputation can answer a protected question. However, the +100 account association bonus is ignored for this check2, so users with the association bonus require 110 reputation to answer protected questions. In other words, all users must have earned 10 or more reputation on that specific site to answer a protected question.
The reasoning about this reputation limit is discussed in Allow people to answer protected questions if they have earned at least some amount of combined SE rep
When should I protect or unprotect a question?
- Do protect questions that are attracting a lot of non-answers or very poor answers (spam, etc.) from new users.
- Don't protect questions just because they're linked to on Hot Network Questions or a high-traffic news site.
- Do unprotect questions that aren't currently attracting a lot of attention and don’t have a long history of unproductive answers.
See also: Changes and guidelines for the Protected Question status
When does the Community user protect a question?
The Community user will protect a question in the following cases:
- The number of deleted answers from users with <10 rep1, plus the number of answers with helpful spam flags, is at least 3. (Note that spam answers from new users are counted twice.)
- Generally, this means that three deleted answers from new users will cause auto-protection, but if at least one of those answers is spam, only two answers will trigger it.
- Five answers from users with <10 rep were posted in the last 24 hours. Three answers on Software Engineering, English Language Learners, and Workplace, and 20 answers on Code Golf.
The system will never unprotect a question automatically, even if the deleted answers are later undeleted or the spam flags are cleared.
Automatic protection notes
- Multiple answers from the same user are counted as just one towards the checks. For example, if three answers from new users are deleted, but if two of those answers were posted by the same user, the question won't be auto-protected unless it gets another deleted answer from a different (third) low-rep user.
- The relevant checks are run whenever any qualifying answers are deleted (for criterion 1) or posted (for criterion 2). This means that if a question that met the criteria for automatic protection is unprotected later, and a qualifying answer is later deleted or posted, the question will be re-protected if it still meets the respective criterion. For example, if a question that receives five answers from new users in the last 24 hours is manually unprotected, if it receives another answer from a new user in the same 24-hour period, it will be re-protected.
- Sites have the ability to turn off auto-protection if they wish. Some per-site metas, especially those with "sandbox" questions, have opted to disable auto-protection.
1 While users with the association bonus but less than 110 reputation aren't allowed to answer protected questions, the checks for automatic protection and whether to allow 15k+ users to protect the question only consider users with <10 rep as "new users", without checking for the association bonus.
2 On per-site metas, this restriction does not apply; if you have the association bonus, you can answer protected questions on per-site metas without needing to earn 10 rep on the main site first (provided your reputation on the main site hasn't dropped below 10).