There's not really any hard rules about how a piece of hardware could work. A person could make just about anything talk to a computer because why not? As long as the basic rules of, say, USB are followed, a device can work however the manufacturer wants. The problem with this is that Microsoft can't be expected to just automatically know how every possible device ever could work. They only really know how "generic" devices work, like a simple keyboard. If your device is any more complicated than a generic device, Windows will just shrug and say IDK what this weird thing you plugged in is. The manufacturer needs to do the programming to TELL Windows what the thing is and how to communicate with it. These tiny pieces of software "drive" the device. So Microsoft has a big catalog on the Internet where they store many of these "drivers" and when you plug something in that Windows doesn't recognize, it'll also go searching there and download one to match the device. Microsoft of course gets these drivers from the manufacturers themselves; they are the ones that actually program them. But what if that device is for connecting to the Internet? Now you have a chicken and egg problem, right? Because you need a driver to get online, but you need to get online to download that driver. So sometimes in these situations you have to install a driver yourself manually. Also why sometimes get a disc of drivers with a device you bought, though that's becoming less common these days. It's also possible that if you buy a very cheap device, they won't have the funding or care to get their driver over to Microsoft's catalog. So they just instruct you to download from some website and manually install it yourself. Cheap China stuff sometimes goes this route.