Jinja2 is a Python package implemented with HTML template language. There're basicly two ways to render a page, one is front-end render, the other is back-end render. As for back-end render, it's usually executed by HTML template, which might contains some logics like inheritance other basic template. The inheritance function of these template logic can leave the support from template language, and Jinja2 is just the language needed. With Jinja2, writing HTML template will be an easy thing to do. In this experiment, we will learn all aspects of Jinja2, like template variables, loop function, filter, etc.