Internet connection rate in 2000 showing the number of connections/10,000 people/country.
Internetworking involves connecting two or more local area networks via some sort of wide area network. The definition now includes the connection of other types of computer networks such as personal area networks.
The most notable example of internetworking in practice is the Internet, a network of networks running different low-level protocols, unified by an internetworking protocol, the Internet Protocol (IP).
IP only provides an unreliable packet service across an internet. To transfer data reliably, applications must utilize a Transport layer protocol, such as TCP, which provides a reliable stream (These terms do not mean that IP is actually unreliable but instead that it sends packets without contacting and establishing a connection with the destination router beforehand. The opposite applies for reliable). Since TCP is the most widely used transport protocol, people commonly refer to TCP and IP together, as "TCP/IP". Some applications occasionally use a simpler transport protocol (called UDP) for tasks which do not require absolutely reliable delivery
