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.
Tags are used to classify questions into different groups. The "tags" tag should be applied to any meta question asking about tags.
The scope of the main site: what questions are on-topic and what is off-topic
should be applied to Meta questions asking about Questions on the main site, or on the meta site.
Questions about how to promote the site and gain more visitors, questions, answers and users.
Questions about adding references and citations to posts
Questions related to the name of the main site (currently it is named "Cognitive Sciences")
Unanswered questions are those questions which have no up-voted or accepted answers.
Questions related to migration, i.e. migrating off-topic questions from Psychology & Neuroscience Stack Exchange to another Stack Exchange site, or from elsewhere to this site.
There are 7 Essential Meta Questions of Every Beta. This tag covers any of those questions.