 Hi, welcome to week 5. So far we have seen about computing and communication technologies. How computation happens on the web server, on the client, how phone calls happen, how data gets transferred over 2G networks, 3G networks and so on. Now the next level of abstraction is given that I can compute and communicate over a phone or a computer, I will use this power to actually interact with members of my society, my friends, my neighbors, my family members and people with same interests. These are called interaction technologies, an example of that is social networking. So this week is all about social networking technologies. Only between any 2 people in the world, there are only 6 intermediaries. In 6 hops I can reach any person in the world. We already know each other, except that there are some people in between and that number of people are limited. So Dr. Runa Sarkar is going to talk to you about it, the 6 degrees of separation and then of course we will see in great detail about Facebook, Twitter and blogs. Prashant Gautam is going to explain blogs to you. We have about 5 lectures in this social networking series. This would be of great interest to all of you because ultimately the basics in competing and communication are used to build these applications. And you can actually start using these technologies because they are ready to use software like Facebook and Twitter. And then subsequently you will realize that I can use these technologies to solve my problems in the domain like in agriculture, use Facebook for agricultural extension, use Twitter for communicating calamities and so on. So this is a very important week, please pay particular attention to what is happening and we have much to follow up on this way. In addition to those we have some advanced topics in the communication space. Some of you have asked for example we want to know more about Bluetooth and so on. So Dr. Aditya Daganatham has put together a set of lectures explaining all these technologies. This will be slightly advanced may involve little electrical engineering. So if you do not understand what is happening in the lectures do not worry but plow through them if possible. We have a quiz, the link is active now it will be active for 3 days, 72 hours So have a go at it, there are some very nice questions which will actually enable you to understand the various concepts that we have talked about. And we have assignments coming this week, be on the watch out, have fun.