Components rely on their templates for rendering their data. Templates are where you define what the component looks like and you can hook in styles to window-dress your component any way you like. A component can either contain its template (that is, the HTML) and its styling (that is, the CSS) either directly within itself or have references to template and style files outside of itself. At the end of the day, the world's fanciest frontend frameworks produce HTML, CSS, and JavaScript because these three things are the only things browsers understand.