"package-lock.json" can someone please define what it is and does, I've heard of shrink wrap, google doesn't reveal anything about this file, I have a vauge ide

"package-lock.json" can someone please define what it is and does, I've heard of shrink wrap, google doesn't reveal anything about this file, I have a vauge idea that it has something to do with shrinkwrap but don't know why it exists or if it's supposed to replace shrinkwrap or whatever. splainit!