Tags and subtags

Tags are embedded anywhere within the note's contents. They're regular
hashtag-tags, i.e. #psychology or #biology, with the restriction that
they're both preceded and succeeded by whitespace.

Subtags are tags which contain one or more forward slashes, i.e.
#psychology/disorders, #biology/anatomy, or
#literature/unprocessed/urgent. These allow you to get more specific with your
tagging, to move from a more abstract subject towards a more concrete idea (or
task).

It's entirely up to you how you organise your tags and subtags, or if you use
tags at all.
