What's the Real Difference Between Private vs Public IP Addresses? or Private vs Public IP Addresses:

Private vs public ip addresses matter cuz of scale. If every toaster had a public IP, we’d need IPv6 yesterday (oh wait, we kinda do).

Public IP = global phone number.
Private IP = walkie-talkie channel in your house.

Your ISP assigns public, router handles private. No config needed unless you’re doing fancy stuff like port forwarding.