UUIDs are neat. y'know, cfbff0d1-9375-5685-968c-48ce8b15ae17 type of shit. if you're like me until a few days ago, all you know about the types of UUID is that v4 is the good one. but why are there other ones? is there a secret better one? why are the dashes asymmetrical? let's take a (roughly paraphrased from wikipedia and probably not quite accurate) look.