Public and Private IP Addresses: What is the difference?

An Internet Protocol (IP) address is a lot like an address or phone number that identifies a device like a computer, smart phone, or printer. If you’d like more information for what an IP is and does, go here – Internet Protocol.

What is a public IP address?

Public IP addresses are used to communicate over the Internet. Like a home address, a public IP addressed is used to determine where to deliver data requested by a certain router.

Generally these IP addresses are signed by the Internet service provider (ISP) by a router and can switch when a computer is connected to a different network. This means that if you and your friend are both connected to the same WiFi, you will be assigned the same public IP address, but will have different private IP addresses.

If you would like to know what your public IP address is, go here: My Public IP


So then, what is a private IP address?

A private IP address cannot be used to contact a computer over the Internet. These IP addresses are used in local area networks (LANs) and do not connect to the Internet so therefore they afford an extra layer of security. Private IPs are also assigned to devices like your home computer so that only you can print to your printer.

Typically, a network address translation (NAT) device will communicate with the Internet to see if incoming data was requested by a computer with a private IP address. If not, the information is discarded before reaching the computer.

The organization that is responsible for handing out IP addresses reserves ranges of IP address for private networks: –; –; – These blocks of addresses can be used by anyone anywhere. The assumption is that since these addresses are only used in private, closed networks, even if your neighbor is using the same range of IP addresses right next door, it will not matter because the two networks will never connect to each other so there will not be a conflict.

If you would like to know what your computer’s private IP, you can check on a Windows system by going to the command prompt and typing in ‘ipconfig’ and hitting enter. If you’re using Linux, go to the terminal and type ‘ifconfig’. Finally, if you’re a Mac user click on the apple, go to ‘System Preferences’, then click on ‘Network’. Under ‘Status: Connected’, it will show the IP address.