HTML gets little respect as a programming language because it's easy. But used properly, it's extremely powerful. Used improperly, as it almost invariably is due to the very little curriculum focus on it, it is slow and stupid. I used CSS Grid to create a mini-Domain Specific Language for Periodic Table of Web APIs.

HTML is a document format. It defines the CONTENT of a webpage. That it has an API or is usually styled is secondary. The semantic tags– as used here, as used to STORE DATA here– are what make it possible to build a kanban solution so easily.

HTML is also a data format. It can be styled through the use of CSS.