Public IP addresses Are all Public addresses connected to each other? Can I ping my friend's public IP address on another side of the world, or are public addresses are divided into groups (something like private and public)? What makes this ping impossible?

Converting comment to an answer.

Public IP addresses are public IP addresses. They are available from any other public IP address across the internet. The only restriction will be if an active host has a firewall or other measures to prevent you from accessing it. Other measures could be a DDoS Filter with Geo blocking, that only allows specific public IP addresses to access its network. Some ISPs and companies use Geo blocking also.