Public vs. Private IP Addresses
A public IP address is intended to be routed across the internet. A private address is intended for use inside a local network. Understanding the difference helps explain why your laptop may show one address while an online service sees another.
Common private IPv4 ranges
10.0.0.0/8172.16.0.0/12192.168.0.0/16
Addresses in these ranges can be reused by many separate networks. Your home may use 192.168.1.20, while thousands of other homes use the same value without conflict because the networks are isolated.
How NAT works
A home router usually performs Network Address Translation. It tracks outbound connections from private devices and maps them through the router’s public address. Return traffic is directed back to the correct device. NAT conserves IPv4 addresses, but it should not be confused with a complete firewall policy.
Carrier-grade NAT
Some internet and mobile providers place customers behind another layer of shared translation. This can make inbound hosting, certain games, peer-to-peer applications, and remote access more difficult. The range 100.64.0.0/10 is commonly used for shared carrier space.
IPv6 local addressing
IPv6 devices may have several addresses, including link-local addresses beginning with fe80:: and globally routable addresses. Firewalls remain essential even when translation is not used.
Which address should you use?
Use a private or local address when connecting to a device from the same trusted network. Use the public address only when configuring an internet-facing service and only after applying authentication, encryption, firewall rules, updates, and logging. Never expose an admin panel directly to the internet without protection.