What distinguishes private IP addresses from public IP addresses?

Private IP addresses are defined as those that cannot be routed over the public internet. They are used for communication within a closed network, allowing devices within that network to communicate with each other without requiring access to external networks. The absence of routability over the internet is what makes private IP addresses distinct, as they are intended solely for internal usage within a local network environment, such as a home or corporate network.

In contrast, public IP addresses are globally unique and can be accessed over the internet, allowing devices using these addresses to communicate with any devices across the internet. This distinction is crucial for understanding network design and security, as the use of private IP addresses helps to create a more secure environment by limiting external access to internal devices and resources.