HTML is a great acronym if you like great lawyer speak. It's a term which has now monopolized the concept of markup, and is a cancer!
HTML is an EMBEDDED markup language. This means that the markup has to be intermixed with the text it is meant to mark up. This direct physical linkage, embedding, of the markup is great of you happen to be the owner of the document, and have the tools to hide the complexity of it's internal representation, but for everyone else, it's hell.
What HTML should been, is a markup language for hypertext. It should allow the markup of an existing SEPARATE document, by reference. Ted Nelson tried very hard to get this idea across to the masses, but when the critical moment came, Tim Berners Lee took the easy way out, and we're all screwed, even though most of us don't even know it.
There are a great many things that are broken as a result of this singularly bad choice. We're forced to rely on spiders to find documents on the world wide web. We have no ability to add commentary directly on top of other people's work, except by extraordinary measures, which break copyright rules.
The embedded nature of HTML has limited our range of thought. It is an example of how the limitations of language impose limitations of range of thought. If you can't imagine being able to highlight a section of someone's blog posting in yellow, with a hyperlink to something else, and a note that says something about the connection, you won't ever miss it.
HTML is evil. I'm open to any discussion about alternatives.