HTML predates XML by 5 years.

What's more, the web standards bodies even abandoned a short-lived XML-hype-era plan to make a new version of HTML based on XML in 2009.

That from this touted to the heavens format a handful of uses remain (some companies still using SOAP, the MS Office monster schemas, RSS, EPUB, and so on) is the very opposite of the adoption it was supposed to have. For those that missed the 90s/early 00s, XML was a hugely hyped format, with enormous corporate adoption between 1999–2005, which deflated totally.

Did you also learned those things too today?