Internetworking is the technology that makes it possible to interconnect many disparate physical networks with diverse underlying hardware technologies and make them function as a coordinated unit. The internetworking / Internet technology hides the details of network hardware and permits computers to communicate independent of their physical network connections. When we speak of interworking technology, we speak of the internet technology in particular.
There are two methods for providing interconnectivity for between communication application programs on different machines. One method is Application level interconnection in which we use application level programs running on each machine that could understand the details of the network connections for the machines and interoperates with the application programs across those connections. Eventhough this method hides the hardware details between source and destination, such an approach to network interconnection has various drawbacks since it requires to change the application software every time when the network functionalities are changes. Also as the network grows larger, it is impossible to code the application program for each interconnected applications.
The alternative approach to this is the Network-level interconnection that provides a mechanism that delivers packets from their original source to their ultimate destination in real time. Such an approach of universal network-level interconnection called the internetworking has the following features. It carries the data as small packets of data that could be easily mapped on the underlying network hardware. It separates the data communication activities from application programs, permitting machines to handle network traffic without understanding the application that use it.
It keeps the system flexible making it possible to build general purpose network protocols. It allows network administrators to add new network technologies by modifying or adding a single piece of new network level software, while application programs remain unchanged. It detaches the notions of communication from the details of network technology and hides low level details from the user. It enables to build unified cooperative interconnection of computer networks that supports a universal communication service and interconnection scheme called the internetwork or the Internet with each machine on the internet having a specific address.