wtf is nostr?

So no question I've been enjoying lemmy, I love the freedom it offers and I love the seemingly simple and elegant framework it runs on however after having ditched Reddit for the hopes of a similar or improved content experience I have to say it is quite a bit smaller and therefore barren at times which is both a good and bad thing depending on your needs

And then of course there's kbin and masterdon which from my understanding is a little more geared towards the twitter-like micro blogging

But this morning somehow I stumbled across nostr which I have never heard of but I was wondering if anyone out there has any experience with it? There's a Web app like voyager at iris.to that makes browsing pretty simple..