IP addresses starting with 192.168., 172.16-31, and 10. are special "unregistered" addresses
for private internal networks not directly accessible from the
Internet. These computers are "hidden" from the Internet by the
router/default gateway which does a translation to and from the
private address to an Internet-accessible "registered" IP address
(this process is called NAT: network address translation).
Also, the port used on the internal host is mapped to a port on the router. PAT.