When learning about GUIDs, it feels like 39 measly digits aren’t enough. Won’t we run out if people get GUID-crazy, assigning them for everything from their pets to their favorite bubble gum flavor?
Let’s see. Think about how big the Internet is: Google has billions of web pages in its index. Let’s call it a trillion (10^12) for kicks. Think about every wikipedia article, every news item on CNN, every product in Amazon, every blog post from any author. We can assign a GUIDfor each of these documents.
Now let’s say everyone on Earth gets their own copy of the internet, to keep track of their stuff. Even crazier, let’s say each person gets their own copy of the internet every second. How long can we go on?
Let me say that again. Each person gets a personal copy of the internet, every second, for a billion years.
It’s a mind-boggling amount of items, and it’s hard to get our heads around it. Trust me, we won’t run out of GUIDs anytime soon. And if we do? We’ll start using GUIDs with more digits.
Copied from: [The Quick Guide to GUIDs]