William Gallagher, AppleInsider:

If you spent any time looking into which Mac desktop or notebook to buy before you paid out for a shiny new machine, you’ll have seen Apple’s website extolling the fact that many of them have T2 security chips. That’s nice. Only, it’s more than nice, it’s more than a way to invisibly secure your Mac, it is a process that has a dramatic and visible effect on just about everything you do.

And:

It sits there to ensure, first of all, that nothing can ever get loaded onto your machine without you explicitly wanting it to. The T2 chip provides a secure boot, which means that the only things that can run at start up is trusted, approved macOS software.

And:

Built into it is a dedicated Advanced Encryption Standard (AES) hardware engine. This makes sure the data on your storage drives is encrypted and because it’s done in hardware, there’s no hit to the speed of your Mac as macOS reads and writes data.

And:

There’s one more security feature the T2 chip brings that doesn’t get appreciated because it doesn’t tend to get noticed. If you have a MacBook Air or MacBook Pro with a T2 chip and you close the lid, the T2 chip switches off the microphone.

Just a few highlights. Read the whole thing. Terrific stuff.