YAML is not as well known as other frameworks like Bootstrap or Foundation. It has been around since 2005 though, with continuous support and development. Version 4 has been completely rebuilt based on Sass. Other reasons to consider it include an extremely slim core, a bulletproof flexible grid system for easy responsive design, a flexible forms toolkit and browser support all the way down to Internet Explorer 6. Simply said, it doesn’t contain a lot of the “bloat” that the bigger frameworks include, and responsive design with YAML is guaranteed to work on every old browser, too.
The YAML community provides templates and other integration options for various open-source content management systems. However, for WordPress there is only a German premium theme framework available. That’s why I decided to release wpYAML under the GPL license, a base theme compatible with YAML I had originally started in 2013.