Relevance

How is the Relevance calculated?
I cannot guess the logic of sorting the courses by the relevance.

I guess they sorted the forum posts by relevance.

Sorting by relevance adds weight to the search term when it appears in the title of the course/lesson.

I am talking about the Course Library tab. By default it shows all the courses sorted by Relevance I do not use any other search criteria.
I don’t undertand.

I know, I am referring to Course/Lesson library tabs too. Sorting by relevance applies only when you search, otherwise it’s just random list.