Some address ranges are reserved for use inside a network. They are not routed on the internet: send traffic to one and the first router it meets discards it.
The private ranges (RFC 1918)
- 10.0.0.0 to 10.255.255.255 — 16.7 million addresses, mostly used by businesses
- 172.16.0.0 to 172.31.255.255 — 1 million addresses
- 192.168.0.0 to 192.168.255.255 — 65,536 addresses, which nearly every home router uses
What NAT does
Your router translates between those two worlds. Traffic from 192.168.1.14 leaves as though it came from your public address, and the router remembers which reply belongs to which device. That is Network Address Translation, and it is why an entire household manages with a single public address.
Other reserved ranges
- 127.0.0.0/8 — loopback: the device itself, usually 127.0.0.1
- 169.254.0.0/16 — link-local: what a device picks when no DHCP server answers
- 100.64.0.0/10 — carrier-grade NAT, used by providers between their customers and the internet
If you see 100.64.x.x as your address inside your own network, you are behind carrier-grade NAT. Incoming connections — a game server, reaching a NAS from outside — will not work without a further arrangement with your provider.