Skype made its first appearance in 2003 and was the brainchild of Niklas Zennstrom, Janus Friisk, Ahti Heinla, Priit Kasesalu and Jaan Tallin. The Skype program, which is now owned by Microsoft, is a free instant messaging client and voice-over-Internet protocol service.
With its name derived from the words "sky" and "peer," Skype had more than 663 million registered users by the year 2010, shortly before it was purchased by Microsoft for $8.5 billion in 2011. The program is widely popular because it allows users to communicate by video using a webcam or by voice chat using a microphone. Calls can also be made to other Skype users for free or for additional charges if the call is made to a landline or cellphone.