Umbraco/Templating/Templates

Templates in Umbraco defines the general layout of the public website, the template combined with a document, outputs a webpage – by ensuring that content and presentation is separated in different layers of the application, it’s guaranteed that you can change one layer without compromising the other. Umbraco itself does not generate any HTML, the webpages of the public website, are 100% generated from the HTML in the templates and data from the documents (for some webpages, a subset of the HTML comes from macros – more on that subject later).

This means that the web developer is 100% in charge of what kind of the HTML output that is served when a user visits the website.