Released in August 2003, Skype is a freemium voice-over-IP and instant messaging service created by Janus Friis and Niklas Zennstrom, in cooperation with Ahti Heinla, Priit Kasesalu and Jaan Tallinn. Microsoft bought Skype in 2011.

The service allows users to communicate with others by voice, video and instant-messaging. Phone calls may be placed both to other Skype users and to recipients with traditional telephone networks.