Powerful, flexible templating
The core feature of a Web CMS is to enable Editors to input and edit web content and merge this with page templates to output attractive and effective web pages. Thus, a CMS's templating features are absolutely critical to the success of the sites that use that CMS.
Umbraco is built using Umbraco, and uses the industry standard Microsoft ASP.Net templating language. Developers write templates using C# or VB.Net, and typically output HTML merging generic templates with content from the Umbraco database using a number of well documented APIs.
Umbraco also supports template output in formats other than HTML, e.g. a template can output AMP format, RSS or XML. In fact it is possible for a page to output content in multiple formats, through the inclusion of an Alternative Template in the URL.