 The history of internet is so interesting that a couple of lectures could be devoted to it. However, for the sake of purposefulness and gravity, I've tried to consolidate the periods of internet evolution in three phases and the latest advancements that we see today. In this module, we'll go phase by phase to understand how the development took place in the evolution of internet. First thing first, the origin of internet is usually attributed to military, but it saw a lot of research investment coming from academia and the commercialization by the industry took it all together to a different level. So combining all these three, no single factor could be attributed all with the success of internet. So essentially it is a hybrid kind of evolution that took place. What we can do is, if you really want to understand and draw lessons from the evolution of internet, we have to go through the phases of internet history one by one so that we can rationalize certain conclusions. Let's look at the first period. Starting from 1960s, the Advanced Research Project Agency, which later was named as DARPA, Defense Advanced Research Project Agency, it started off with the concept of using internet and the primary goal was to secure installations, primarily military installations in Hawaiian islands in the US. The famous project known as Aloha is attributed with the foremost project at DARPA. Later, Professor Leonhard Kleinrock from UCLA did his PhD and gave the concept of packet switching and did a theoretical or in other words a probabilistic analysis of how packet switching is going to behave versus circuit switched networks. In 1969, the first internet ready computer host was established. In 1969, two nodes, one at UCLA and the other one as Stanford Research Institute were connected to transfer basic textual message. In 1969 again, Steve Crocker came up with the idea of request for comment. Request for comment is a system through which the participating agencies involving government, industry and academia can all chip in and share their findings at a unified platform through which standardization could take place and this standardization was overseen by the Internet Engineering Task Force. In 1972, the first email program was written by Ray Tomlinson and Larry Roberts. This email was based on a protocol simple mail transfer protocol. In 1974, Windsurf and Robert Kahn created TCP and later IP. In fact, I had the honors of meeting Professor Windsurf in a conference, I think it was Scotland, it was Ireland. There, Professor Windsurf was just a chair who was hosting and inaugurating various sessions. In 1980s, the user datagram protocol was standardized. UDP is another protocol that sits at the transport layer next to TCP. It provides services. In fact, it does not provide any service. That is why it is well suited to the transmission of real-time content. Anyways, UDP is one of the most widely used protocols these days for real-time transmission of voice and video. In 1981, the RFCs for IP and TCP were approved at the ITF. In 1982, the domain name system that translates the human understandable domain names into computer understandable IP addresses and vice versa was approved. In 1983, there were around a few hundred nodes in U.S. All these hosts were using a protocol called network control protocol. This NCP was replaced by UNIX Berkeley software distribution company and they replaced it with TCP IP. The third period is actually the emergence of the worldwide web. This WWW is actually the web of pages which are hyperlinked together. This forms a mesh of information network. So, in 1989, Tim Berners-Lee's discovery or invention at CERN lab is considered to be one of the groundbreaking moments in the history of internet. In 1993, this WWW concept was made public and people were encouraged to create content of their own and host it over the internet. In 1993, the dynamic host configuration protocol that allows the IP address assignment to these laptops whenever you enter into a Wi-Fi zone was approved. In 1996, the hypertext transfer protocol version 1 was approved in this RFC-1945. And in 1998, the migration with much desired migration for IP version 4 to IP version 6 was realized. IP version 6 was meant to solve the famous Rhodes problem that is running out address space. In very recent years, we have seen some torrents and peer-to-peer networks to appear. I have witnessed the time when we used to have an application called Napster. It was kind of a peer-to-peer torrent kind of network that would allow the audio and music files to be shared between the peers of a certain network. However, because of copyright violation, it was banned in the US and subsequently in the whole world. There was another file sharing system called eDonkey in 2000. Skype came as a watershed because this was the moment when voice over IP through Skype became widely accepted and got so prevalent that it gave a financial dent to different telecommunication companies in various countries. And very recently, we have experienced the torrents. The BitTorrent is a file sharing system that is based on peer-to-peer protocol. So you see, the concept of the evolution of technology owes its origins somewhere into these protocols and how these applications were developed by various professors and scientists.