I had a brief look at the websites this page links to, and some of them fail to mention what they're about. Blockstack tells me their token sale has ended. But

I had a brief look at the websites this page links to, and some of them fail to mention what they're about. Blockstack tells me their token sale has ended. But what the hell is blockstack and why should I care about its token sale? Matrix is an open network for secure communication? What does that even mean to regular joe?