How to use Tags
When tagging notes within a zettelkasten system  and elsewhere, the tags should help in retrieval rather than archival.
This means that the tags should aid the user in finding the notes, rather than simply giving structure to the notes by organizing in some implicit categorization.
We can achieve this by using the tags to provide context to the notes. Ask yourself, in which circumstance would it be convenient to find this note? This suggestion is also found in Getting Things Done .
For example, we may tag a task that we can only complete while using a computer with the tag “computer”. This allows us to know exactly what we need to do when we are using a computer.
 Ahrens, S. (2017). How to Take Smart Notes: One Simple Technique to Boost Writing, Learning and Thinking for Students, Academics and Nonfiction Book Writers. Sönke Ahrens.
 Hamberg, E. (2010). GTD in 15 minutes to Getting Things Done.