@docpop I usually say the fediverse is built on ActivityPub, an "open standard" for social media. (Then I might go into how html is the technology that drives the web, but all the different browsers implement various "open standards" for rendering html, or websites would look different between Firefox, Chrome, and Safari.) Mastodon is just one open source implementation of this standard, but there are lots of others! And lots of websites host mastodon, just like word press.
docpop