What is the difference between public and private IP addresses?

Public IP addresses are globally unique and accessible over the internet, while private IP addresses are used within local networks and not directly accessible online.

Public IP addresses are assigned by the Internet Service Provider (ISP) and are used when you connect to the internet. These addresses are unique across the entire web, ensuring that all devices connected to the internet have a distinct address. This is similar to your home address, which is unique and allows mail to be delivered correctly. Public IP addresses are used for websites, servers, and any device that needs to be directly accessible over the internet.

On the other hand, private IP addresses are used within a local network such as a home, office, or business. These addresses are not directly accessible from the internet; they are hidden behind a router or other network device that uses Network Address Translation (NAT). This means that many devices can share the same private IP address, as long as they are on different networks. For example, the IP address 192.168.1.1 is a common private IP address and can be used in any number of separate networks.

The main reason for the existence of private IP addresses is to conserve the limited number of public IP addresses available. With the proliferation of devices needing internet access, the IPv4 addressing system (which most public IP addresses still use) is not capable of providing a unique address for each device. By using private IP addresses within local networks, only the router (or similar device) needs a public IP address. All other devices on the network use a private IP address, with the router managing traffic and connections to the internet.

In summary, public IP addresses are unique, globally accessible addresses used for devices connecting directly to the internet. Private IP addresses are used within local networks, are not directly accessible from the internet, and can be reused across different networks.