Public vs private IP addresses: what is the difference?
A public IP address is used for communication across the Internet and must be unique within the public routing space. A private IPv4 address is intended for a local network: the same address, such as 192.168.1.10, can be used in different homes at the same time. To understand an address shown in settings, distinguish the device, router and provider.
Which IPv4 ranges are private?
RFC 1918 reserves three ranges: 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16. Home routers often use the last one. The 172.16.0.0/12 block runs from 172.16.0.0 through 172.31.255.255; an address is not private merely because it starts with 172. These addresses can be reused in separate local networks, so ordinary Internet routers do not carry packets to them as globally reachable destinations. 127.0.0.1 is a loopback address and 169.254.0.0/16 is link-local: neither is one of the three RFC 1918 ranges.
Where to check your device and external addresses
Your device’s network settings show the address of its Wi-Fi or Ethernet interface. That address may be private. The router’s status page shows the address on its external interface, while the 2ip IP information tool shows the address from which your request reaches this website. Compare the values. If the router’s external interface has a private address, another router or translation layer is upstream. If the website sees a different address from the router’s external one, the cause may be a VPN, proxy or carrier-grade NAT.
How NAT fits in
A home router commonly translates outgoing connections from several privately addressed devices onto one external IPv4 address. It tracks each connection and sends replies back to the right device. That is why a website may see one IP address for several phones and computers. NAT is not itself a complete security policy: incoming access also depends on firewall rules and port mappings. If you want to host a service at home, knowing the external IP is only the first step.
Example and important limits
A phone uses 192.168.1.20 while its router has a public Internet address. A second household may have a phone with the same private address without conflict, provided the local networks remain separate. If the router’s external address lies in 100.64.0.0/10, that is shared address space for provider networks, distinct from the RFC 1918 private ranges. A public address does not reveal an individual’s identity or precise location; it may change or be shared. Check the complete network path before drawing conclusions from one number.