A Jinja template is simply a text file. Jinja can generate any text-based format (HTML, XML, CSV, LaTeX, etc.). A Jinja template doesn’t need to have a specific extension: .html, .xml, or any other extension is just fine.
A template contains variables and/or expressions, which get replaced with values when a template is rendered; and tags, which control the logic of the template. The template syntax is heavily inspired by Django and Python.