Wikipedia:Obscure does not mean not notable

An obscure topic is a topic that is only of interest to a small number of people, such as those in the subject's field, teachers, or fans. Obscure topics are perfectly welcome to have articles on Wikipedia, provided that notability guidelines are met.

Why do we need this essay?
Generally, we hope that each article can be easily read by the general audience and useful to a professional audience concurrently (see and The perfect article). However, there are situations where topics the general audience do not need to know and would not ever understand, such as qubit field theory and many advanced topics in mathematical and natural science not mentioned in general university-level textbooks, e.g. general calculus university textbooks, but the professional audience may want them to be articles since they consider them useful or interesting. In Wikipedia they can be articles, but when the articles are written and editors try to let general readers understand them, they probably cannot have enough details to satisfy professional readers entirely. This is the reason that this guideline is established.

When writing this type of article
In circumstances where using layperson's terms and fully satisfying professional readers' needs are impossible or nearly impossible, editors should only meet professional readers' needs and just let general readers know the significance of the field to which the topic belongs. However, if editors find out a way to use layperson's terms and fully satisfy professional readers' needs at the same time, this guideline should not be applied.

Obscurity is not grounds for deletion
When an article meets WP:N or any other guidelines for inclusion, the mere fact that its subject is obscure does not under any circumstances mean it should be deleted. See also WP:IDONTKNOWIT or NOBODYREADSIT.