What is the T2 Security Chip on modern MacBook's

(August 1, 2019) At some point Apple designed the MacBook's and MacBook Pros with the T2 Security Chip. It's just there, and supposedly it's a good idea. But like all things, it's useful to know what the chip does, and more importantly why Apple designed this chip into the system. Supposedly it increases security, otherwise why is it called the Security Chip, but is there another purpose. Apple is famously tight-lipped about its roadmap, so what if this is a game of multi-dimensional chess where the T2 chip is a harbinger of something else?