IP address

Public IP address:

Public IP Addresses (also known as Static IP Addresses) are IP addresses that are visible to the public.
Because these ip addresses are public, they allow other people to know about and access your computer, like a Web server.
In some cases, you do not want people to access your computer or you want to restrict certain individuals from accessing your computer or server.

Private IP address

These addresses can be used on a private network, but they’re not routable through the public Internet.
This not only creates a measure of much-needed security, but it also conveniently saves valuable IP address space.

Current Private IP addresses range:

Class A
10.0.0.0 through 10.255.255.255
Class B
172.16.0.0 through 172.31.255.255
Class C
192.168.0.0 through 192.168.255.255

Source