No, it’s not official in any formal capacity. Yes, it’s also called Blogging Day, Blog Day, International Day of Bloggers, and various other things. I almost forgot all of them, but Antranig Vartanian reminded me on Mastodon with kind words that will will not go unchallenged!
Back in 2002, Dave Winer defined the
blogChannelModule namespace, which can still be seen declared on a few RSS feeds:
<rss version="2.0" xmlns:blogChannel="http://backend.userland.com/blogChannelModule">
The URL no longer resolves, like much of RSS’s early infrastructure. But fortunately Feedforall documented some of the elements. My favourite is blink:
<blogChannel:blink> The url of a blog the blog publisher is promoting
It’s my hope that someone, somewhere, has implemented a UI for this feature in their reader or aggragator, and see this link pop up. A side project I’m working on right now sure does! But discussion of that is for another time.