[Aperocky]

Language prediction model is not a closely guarded secret, I suggest looking into academic papers about what they are and maybe even see/do some implementation yourself.

There are no magic, it is just a more complicated transpose, created by training over perhaps 10% of all available text on the internet.

It does have a lot of use, for one I think it would probably put grammarly out of business, and maybe even do some work for law firms.