Skype (/ˈskaɪp/) is an application that provides video chat and voice call services. Users may exchange such digital documents as images, text, video and any others, and may transmit both text and video messages. Skype allows the creation of video conference calls. Skype is available for Microsoft Windows, Macintosh, or Linux, as well as Android, Blackberry, and both Apple and Windows smartphones and tablets. Skype is based on a freemium model. Much of the service is free, but Skype Credit or a subscription is required to call a landline or a mobile phone number. At the end of 2010, there were over 660 million worldwide users, with over 300 million estimated active each month as of August 2015. At one point in February 2012, there were thirty four million users concurrently online on Skype.

First released in August 2003, Skype was created by Swedish Niklas Zennström and Danish Janus Friis, in cooperation with Ahti Heinla, Priit Kasesalu, and Jaan Tallinn, Estonians who developed the backend that was also used in the music-sharing application Kazaa. In September 2005, eBay acquired Skype for $2.6 billion. In September 2009,Silver Lake, Andreessen Horowitz, and the Canada Pension Plan Investment Board announced the acquisition of 65% of Skype for $1.9 billion from eBay, which attributed to the enterprise a market value of $2.92 billion. Microsoft bought Skype in May 2011 for $8.5 billion. Its Skype division headquarters are in Luxembourg, but most of the development team and 44% of all the division's employees are still situated in Tallinn and Tartu, Estonia.