When a question is closed, no additional answers may be posted to it. A user who votes to close a question must select one of the following reasons:
- Exact duplicate
- Off topic
- Belongs to meta.cstheory.stackexchange.com
- Subjective and argumentative
- Not a real question
- Too localized
Since questions on cstheory.stackexchange.com are expected to be research-level questions in theoretical computer science, “off topic” means anything that fails to satisfy this criterion.
Even a question in theoretical computer science will be considered as off topic if, for example, it is too basic to be research-level. Forget about the system-generated boilerplate message.
A question being closed as off topic means that the question does not belong to cstheory.stackexchange.com. It does not necessarily mean that the question is bad. For example, a question about programming (actually writing code) will be probably closed as off topic on cstheory.stackexchange.com even if it is very interesting.
For general information about closed questions and the meanings of other close reasons on Stack Exchange websites, please refer to this post on Meta Stack Exchange.