"Subject isn't notable."

Unfortunately, notability is a pretty ambiguous term. It may sound like a value judgment on the importance of that topic.

On Wikipedia, though, a notable topic is one that has a lot of reliable sources covering it. When a topic isn't notable, it means that there's not enough written about it to cite on a Wikipedia article.

A notable topic preferably has 3-5 sources, independent of the subject (think back to the conflict of interest slide!), and with a reputation for fact checking and/or peer review. The mention has to be more than just a sentence. A chapter or an entire book is probably enough.

Notability is particularly important when you're seeking to create a new article from scratch.

These requirements can make it difficult to create articles about rural areas of developed countries. And there are challenges to writing biographies or histories among underrepresented groups, or many topics about women.

However, with the assistance of a bibliography and your instructor's expertise and that of your school's librarian, you might be able to connect good sources to an unwritten topic. If so, your contribution is part of the crucial, ongoing process of expanding Wikipedia's coverage in these areas.