Questions about the process of closing a question.
Voting to Close is the process by which users can vote to close a question. You gain the ability to cast close votes when you reach 500 reputation. You can also view and cast close votes on your own questions if you have at least 250 reputation.
Use the close-votes tag for questions about the process of closing a question. To discuss the reasons one might vote to close something, use close-reasons. To discuss the general idea of closed questions and other topics about the feature, use closed-questions.
Questions should be closed by casting close votes if:
they are sufficiently similar to existing questions and would be answered identically to them
they are unclear, too broad, or otherwise problematic to identifying the problem in a way that can be properly addressed by answerers
they are sufficiently off-topic, as outlined in the help center
It takes 5 votes to close a question. Gold tag badge holders can single-handedly close and reopen questions as duplicates (source), and diamond moderators can instantly close or reopen any question.