 Whenever people discuss which are the pioneering protocols for the internet, the question is always put in a certain context. For instance, the protocols which make the internet run or the protocols which serve the end users. For now, we are going to discuss and limit our discussion from the point of internet working. For that, we first determine the motivation that led to the emphasis on the implementation of certain protocols and then we'd quickly go over such protocols. Internet as a network of networks starting from the days of ARPA, DARPA and then its implementation at the Stanford University and Berkeley. Internet has evolved and it has evolved tremendously. The most important aspect of this evolution has been the need. To begin with, it was as simple as a simple delivery mechanism. Over time, it evolved into more user driven and network constraints aware protocol. So we saw that there was a time when the internet did not mandate much reliability and we see today when we are talking about running e-commerce and life saving applications on the internet, there's a requirement of immense reliability. The first ever user application, the SMTP was based on a concept of mutual trust that everyone's innocent unless proven otherwise. But as we see today with the kind of infringements and security breaches very severe and strict security measures must be put in place. And we also see that the internet which was primarily meant for elastic traffic involving the transfer of email and browsing over HTTP. It has now emerged as the strongest contender and carrier of audio visual traffic. So the journey from elastic traffic to the inelastic traffic which is delay intolerant has taken its own journey and the protocols have evolved correspondingly. Now if a single protocol were to represent the operation of the internet it would be IP or there's the name suggests the internet protocol. It is the workhorse that delivers user data from one point to the other. Regardless of who the users are, what is the underlying network? What traffic is being carried from a user to another user? IP is based on the only concept of wires which are connecting different routers. So the core of IP is to deliver packets or in other words, packetized communication. Since IP is not bothered about what lies beneath it or what is above it it assumes that all it has to do is deliver best effort without giving any guarantees or assured delivery mechanism to the upper or lower layers. After IP, the two important protocols which have seen the widest deployment so far are the user datagram protocol and the transmission control protocol. I call it the journey from nothingness to so many things. For instance, UDP was only encapsulating user data which was coming at the application layer and was passing it as a packetized data to the internet protocol layer. The IP layer would append its own addressing information to it and would send it on to the wire. But we have seen that this nothingness was initially thought to be of not much use. Slowly, with the requirements of reliability coming up, we have seen TCP having a more important role in terms of providing flow control so that a fast transmitter does not overwhelm a slow receiver. The network that carries traffic on behalf of so many users to so many users is not choked in the wake of increased traffic flow. The data which is to be delivered from one party to the other has to be reliably delivered. It means that the data transmission cannot be just assumed to be a bet. Some kind of assurance mechanism had to be put in place. TCP does all that and finally TCP is also responsible to ensure that the data is delivered in certain order. An interesting comment on both the UDP and TCP is that although UDP literally provides nothing but in reality most of the audio visual applications use UDP because of its simplicity and because of the fact that these AV applications do not require their data to be thwarted. On the contrary TCP is such a well articulated and well designed protocol that any fast rate application that is transmitting at a rate beyond it should be is thwarted and is cut to its size. So we see that most of the AV applications which require continuous and smooth streaming of traffic are based on UDP.