If you have an iPhone, you've seen the message bubbles when you get a text are either blue or green. The blue means that it was sent from an iPhone, green means that it wasn't.
As an iPhone user, this doesn't affect you much, unless you're like me, and you like to send messages from your desktop computer. If someone is a green, you can't, if they're blue, you can. I have about an even mix of green and blue people, although that's unusual, because most people aren't on Apple phones, just like most of them aren't on Apple computers
The vast majority of Smart Phones out there, like computers, aren't Apple products, they run on an open platform. Most Smart phones run on a system called "Android" just like most desktop PCs run on "DOS" (short for QDOS, which stands for the Quick and Dirty Operating System - no one calls it that anymore, for obvious reasons!). Apple phones run on iOS (which stands for Internet Operating System) and Macs run on OS (which means Operating System, as if no other operating system existed).
Apple is a competitor of Android and DOS, so while it plays fairly nicely with them, it plays much nicer with other Apple products. And I just discovered last summer that it means that I can send more stuff faster, including large files, like videos, to my blue people (iPhone). My green people can still get stuff from me, but not quite as much. Yes, it's an unfair system, and Apple really isn't playing fair.
As a Graphic Designer, I've been spoiled for decades using Apple products. They cost a whole lot more than the competition, and if I didn't need it, I wouldn't pay for it. But I've gotten used to it, and it's my world now. I have an iMac, an iPad, and an iPhone. I even named my dog Macintosh!
Apple people are a little bit crazy, and spoiled rotten. I'm so used to it I'm often not aware how the majority of the world lives. Apparently they're green, and I'm blue.