Short answer
A public IP address is reachable on the internet. A private IP address is internal to a home, office or local network.
How private IP is used
Your router gives private addresses to computers, phones, TVs and other devices. These addresses can be reused in millions of homes because they are not unique on the internet.
How public IP is used
The public address sits on the outside of the network. It is used when traffic goes to and from the internet. Websites normally see the public address, not each device’s private address.
NAT connects the addresses
NAT, Network Address Translation, translates between private addresses and the public address. This lets many devices share one public IPv4 address.
Common questions
Are 192.168 addresses public?
No. 192.168.x.x addresses are private and work only inside local networks.
Can two people have the same private IP?
Yes, in different local networks. Public IP addresses should be unique on the internet.