The Internet didn’t come into being all at once. While it is the result of a rather comprehensive national project to establish a resilient data and communications network, it was also constructed from a set of pre-existing networks that decided to exchange information using a common language or protocol.
That “language” is called “Internet Protocol” and it uses a set of addresses called “dotted quads” which are expressed as four one, two or three digit numbers separated by “dots” or periods. One such address is 192.168.1.1 which can be the unique address of any machine on a local network. The last two digits indicate it might be a gateway address as well, since many gateways are set up as the first local machine on a network. Others might be something like 192.168.1.1, such as 172.16.1.1 or 10.0.0.0
Local or Long Distance?
This address system was designed so every computer on the Internet could have a unique address like 192.168.1.1 Eventually, the administrators in charge of the growing world wide web realized that every network still had to conduct some of its business locally, even though it was using Internet Protocol to communicate. So the concept of a non-routable address was invented. 192.168.1.1 is a non-routable address. So is any address that begins with 172.16 or 10.
Who Owns This Computer?
A non-routable address is one that the Internet has agreed (through its protocol) cannot be sent from network to network. Messages to or from these addresses can only be sent or received by computers on the same local network. Inter-network routers are all set up to simply drop their packets.
A Private Network
The non-routable IP address was set up as a standard way for any IPv4 or Internet Protocol Version 4 network to set aside certain local machines with an address like 192.168.1.1 that can be reached through the Internet Protocol but that should not send that information out to the larger Internet. The new IPv6 system will include similar addresses for similar reasons.
The private networking system makes the combination of many networks into one possible and thereby makes the Internet a reality.