 Moving towards next generation networks, it is going to be quite interesting to look at how the traditional internet has been shaped up. In this module, we'd look at some of the enabling technologies. We also call them as enablers that helped us to look at internet, how it is shaped as of today. Then we'd look at the confluence of different networks, such as voice, video, and data, onto a single internet platform that makes internet to be like a socket. We'd look at all these terminologies here. To begin with, internet did not appear in overnight. It evolved from typical communications and communication technologies that strongly pushed the transmission of data between users for various applications. The users got excited when they realized that internet can be used as a means to transfer any kind of data between any user as long as data is represented in packets and as long as it complies to certain protocols which are the essentials of the internet. Internet saw that the existing networks which were supporting telephony, data, video, and audio, and, of course, messaging, were living in isolation. For instance, PSTNs were there for voice. For mobile, we had PLMNs. For data, we had these beeper networks. For video, we had the cable and the satellite networks. For audio, we had the audio broadcasting stations, as in FM and AM broadcasting stations. And messaging was also supported through, for instance, beepers. So internet realized that if all these technologies could be translated into packetized data streams, internet could provide a means for sharing this information amongst a variety of users. So slowly, we saw that the heterogeneous networks living in isolation disappeared, and internet came in the forefront. Of course, the beauty of internet is that it allows various devices with different sizes, shapes, and form factors can coexist as long as they're compatible with the internet. And internet does not care or doesn't bother much about what is the transmission medium. Radio, fiber optic, or electrical conductors could all be integrated into the internet. This leads us to considering internet as a socket. If you recall, in the electrical systems, we have the power plugs and the sockets, which when joined together result into the usage of electrical appliances for a variety of purposes. Here too, internet acts like a socket, where regardless of the underlying infrastructure, regardless of the type of data which is to be carried, internet provides a seamless means. The strength of internet that allows it to do so primarily owes to the protocols, especially at the network layer and the upper layers. For the lower layers, it is only a matter of integrating the underlying medium through a proper hardware technology.