^{Originally posted by bph February 8, 2023}
WordPress 6.2 introduces the first component in a new HTML processing API. Before WordPress 6.2, the block markup was typically updated using regular expressions or the DOMDocument class. Both have downsides. The former is tedious and prone to security issues, while the latter uses libxml2 which does not support HTML5. (Adam Zielinski)

Beyond the Dev Note, it would be beneficial to PHP developers if there is a longer in-depth post on the Developer Blog.

cc: @adamziel , @dmsnell, @justintadlock