DOS/4GW and Protected Mode
We'll start our conversation by saying that DOS/4GW is a DOS extender. That means DOS/4GW is a program responsible for adding some useful stuff on top of the vanilla DOS kernel you have installed on your system. And look, I know this does not really answer anything yet, but we'll get there.
Let's begin our journey trying to understand why DOS needs extending in the first place.
I definitely remember seeing DOS/4GW a lot when playing MS-DOS games back in the '90s, but I had entirely forgotten about it. This article is from 2021, and explains what it is, and why it was needed.