Best Practice for Context Processors vs. Template Tags?

Question

In which cases is it better to create template tags (and load them into the template), than creating a context processor (which fills the request automatically)?

e.g. I have a dynamic menu that has to be included into all templates, so I'm putting it into my base.html. What is the preferred usage: context processor or custom template tag? And why?

Answer 1

Context processors is for putting data (information, content, objects) into the context used to render page.

Template tags are for formatting or processing that content.

A template tag that makes up new data is confusing. Not impossible or wrong, but very confusing.