Skype is an IP telephony service provider that offers free calling between subscribers and low-cost calling to people who don't use the service. In addition to standard telephone calls, Skype enables file transfers, texting, video chat and videoconferencing. The service is available for desktop computers, notebook and tablet computers and other mobile devices, including mobile phones. A number of companies, including Skype, produce dedicated Skype phones.
Included in the free service is a softphone application that can be downloaded to any computing device running Windows, Macintosh, Linux, or Windows Mobile operating systems. A function called SkypeOut enables calls to regular telephones; these calls are charged to a prepaid account or to a flat-fee annual subscription.
Skype's benefits, beyond the free and low-cost calls, are said to include easy set-up and good audio quality. To use Skype from a desktop computer, you just plug in a headset, a specialized VoIP phone or a regular phone (via an analog telephone adapter). You add contacts similarly to the way you do for instant messaging and then, to make a call, just click the icon next to the contact.