Short answer
Public IP addresses are globally unique and allow devices to communicate across the Internet, while private IP addresses are reserved for internal network use and cannot be routed directly over the Internet. Network Address Translation (NAT) enables private addresses to access public networks. RFC 1918 private ranges and the NAT example here specifically describe IPv4; IPv6 has different local-address rules. 1 2
Public and private IP addresses serve separate roles within network addressing, with private addresses relying on public addresses for external connectivity.
On this page
At a glance
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| Question | Public IP address | Private IP address |
|---|---|---|
| Feature | public IP address | private IP address |
| Scope | Global Internet | Local network only |
| Direct Routing | Routable across Internet | Not routable on Internet |
What each thing is
Public IP address. A public IP address is a globally unique identifier assigned to a device, enabling direct communication over the Internet and facilitating routing between different networks worldwide. 2
Private IP address. A private IP address is an identifier used within a local network, not routable on the public Internet, and intended for devices communicating internally within an organization or home. 1
Key differences
The primary technical distinction is address scope: public IP addresses are globally unique and routable across the Internet, while private IP addresses are only unique within a local network and are not routed externally. 1 2
How to tell them apart
You can often recognize a private IP address by its range (such as 192.168.x.x or 10.x.x.x in IPv4), which are reserved for internal use. However, without network context, a number alone may not reveal its type, especially across protocol versions. 1
Where they overlap
In IPv4, a device can use a private address locally while a router translates its outbound connection to a public address. IPv6 has a different local-address framework and usually does not require that IPv4-style NAT pattern. 1 2
Edge cases
A tricky case arises when a device with a private IP address needs to access the Internet. It cannot do so directly; instead, a router with NAT translates its private address to a public one, masking the original address from external networks. 1
Why the distinction exists
Private IP address ranges were established to conserve the limited pool of global IPv4 addresses and reduce routing complexity, allowing many organizations to reuse the same internal address ranges without conflict on the wider Internet. 1
Common misconceptions
A common misconception is that all IP addresses are globally unique and reachable from anywhere. In reality, private IP addresses are intentionally duplicated across countless networks and are blocked from direct Internet routing. 1 2
Examples
When you connect a laptop to your home Wi-Fi, it receives a private IP address from your router. To visit a website, your router uses its public IP address to communicate with the Internet, translating between the two using NAT. 2
Sources
Sources checked October 3, 2026.
- ARIN RFC archive — RFC 1918: Address Allocation for Private Internets. Private IPv4 address ranges.
- Cloudflare Learning Center — What is an IP address?. IP address role and public/private distinction.