[MUSIC] In this module, we'll study about Skype, YouTube, and the technology that Skype and YouTube uses. Further details will be also included in the following module as well. We will start this with discussion on Skype. Skype is a service that supports video chat and voice call service applications with a well known logo, that you see right here. The terminology of Skype was derived from the work sky and peer-to-peer, and you can see that it resulted in a very cool name. Skype communicates voice using a microphone, speaker, video webcam over the Internet. So therefore, these modules come together over interaction with Skype. Skype's architecture is based on a hybrid peer-to-peer mechanism. In addition, it is also using a client and server mechanism as well. The audio codecs supported include the G.729, SVOPC, SILK, and Opus. The video codecs supported include H.264, which we will talk about in further details in this lecture. And the supporting applications are Voice-over-IP, video conferencing, instant messaging, and file transfer, all of the important things are in here. That's why we need to study this in further detail. Skype video conference calls can be made from various platforms using smartphones, tablets, PCs and various other devices. The client operating system for a desktop is supported by these units. As you can see, the series of evolution of Windows products are included. The Universal Windows Platform Client Operating Systems include Windows 10 and Windows 10 Mobile, as well as HoloLens which you see this device right here. This is an augmented reality device which I also use in my research and development in my lab with my grad students. One of the things about augmented reality is that it supports video and various other techniques, and it is a wonderful platform, for Skype based video conferencing as well as other augmented reality applications. Other desktop operating systems include OS X, Linux, including Ubuntu, Linux Alpha, and other versions as well. Skype for other mobile device operating systems include the iOS for Apple's iPhone and iPad, Android, BlackBerry 10, Fire OS, Nokia X, and previously available for selected Symbian and BlackBerry operating system devices. Skype calls to other Skype users within the Skype service are free. However, Skype can also be used in making traditional phone calls to landline telephones and mobile phones, for a debit based user account charge using Skype credit or by subscription. Similar technologies that support voice over IP and video conferencing include SIP and H.323 based services. For example, used by companies like Linphone and Google Hangouts. Looking into the history of Skype. In 2003, Skype was founded by experts and developers that contributed from Sweden, Denmark and Estonia. In 2003 August, the first public beta version of Skype was released. Then, in 2005, Skype made an agreement with the Polish web portal and enabled integration in to the Polish market. Then, one of the big turnaround points was in 2005 September, where eBay agreed to acquire Skype Technologies SA for approximately $2.5 billion. Then, in 2009 September, based on Skype's value which was evaluated at $2.75 billion, eBay announced that it was selling 65% of it, which is $1.9 billion worth of. In 2010, Skype had 663 million registered users. So you can see the tremendous growth and dependency on this cool app that was newly created. Then, a big turn around point was in 2011 where Microsoft acquired Skype for $8.5 billion, and began to integrate Skype services into various Microsoft products. In 2013, February, Microsoft introduced Office 2013, which included 60 Skype world minutes per month in the Office 365 consumer plans, which was for home and personal and university usages of Skype. This made it extremely popular, and it helped promote both the product itself, as well as Microsoft technology products. In April of 2013, the Windows Live Messenger instant messaging service was phased out in favor of promoting Skype. Then, in November of 2014, Microsoft announced that Lync would be replaced by Skype for Business in 2015. Later versions include combined features of Lync and the consumer Skype software. E-organizations were given the option to switch their users from the default Skype for Business interface to the Skype for Business interface. These are the references that I use and I recommend them to you, thank you.