Skype (IPA2: skaɪp) is a software application that allows users to make telephone calls over the Internet. Calls to other users of the service and to free-of-charge numbers are free, while calls to other landlines and mobile phones can be made for a fee. Additional features include instant messaging, file transfer and video conferencing.

Skype was written by Estonia-based developers Ahti Heinla, Priit Kasesalu and Jaan Tallinn, who had also originally developed Kazaa. The Skype Group, founded by Swedish-born entrepreneurs Niklas Zennström and Janus Friis, has its headquarters in Luxembourg, with offices in London, Tallinn, Tartu, Stockholm, Prague, and San Jose.

One of the initial names for the project was "Sky peer-to-peer", which was then abbreviated to "Skyper". However some of the domain names associated with "Skyper" were already taken. Dropping the final 'r' left the current title "Skype", for which domain names were available.

Skype has experienced rapid growth in popular usage since the launch of its services. The company was acquired by eBay in September 2005 for $2.6 billion. EBay has written Skype down to $1.7 billion on its books and announced a public stock offering for 2010 to spin Skype off as a separate company.

Features

main: Features of Skype

SkypeIn allows Skype users to receive calls on their computers dialed by regular phone subscribers to a local Skype phone number; local numbers are available for Australia, Brazil, Chile, Colombia, Denmark, Dominican Republic, Estonia, Finland, France, Germany, Hong Kong, Hungary, Ireland, Italy, Japan, Mexico, New Zealand, Poland, Romania, South Korea, Sweden, Switzerland, the Netherlands, the United Kingdom, and the United States. A Skype user can have local numbers in any of these countries, with calls to the number charged at the same rate as calls to fixed lines in the country. Some jurisdictions, including France and Germany, forbid the registration of their telephone numbers to anyone without a physical presence or residency in the country Fact: date=December 2008.

Video conferencing was introduced in January 2006 for the Windows and Mac OS X platform clients. Skype 2.0 for Linux, which was released on March 13, 2008, also features support for video conferencing. Skype for Windows, starting with version 3.6.0.216, supports "High Quality Video" with quality and features (e.g. full-screen and screen-in-screen modes) similar to that of mid-range videoconferencing systems. Skype conferences currently support up to 25 people at a time, including the host.

The word 'Skypecasting' is a portmanteau of 'Skype' and 'broadcasting'. Its original usage referred to recording Skype voice over IP voice calls and teleconferences. The recordings would be used as podcasts, which allow audio or video content to be syndicated over the Internet. Skype launched a "Skypecasts Beta" service in 2006 where it remained in beta until its end in September 2008. Skypecasts hosted public conference calls, up to 100 people at a time. Unlike ordinary Skype p2p conference calls, Skypecasts support moderation features suitable for panel discussions, lectures, and town hall forums. Skype operated a directory of public Skypecasts. On August 26, 2008, Skype announced that Skypecasts would be discontinued beginning September 1, 2008. 1 September 2008 at 12:00 GMT, Skypecasts were shutdown without any concrete explanation.