Skype is a software program known as a softphone - a computer program that enables one to make calls on a computer over the Internet. Skype is one of many soft phones that makes use of VoIP (voice over Internet protocol). However, Skype is showing itself to be the most popular choice (more than 70 million users worldwide), and about 90 percent of Skype's users are using it on PCs. (By contrast, Vonage, which is different in that it requires hardware in addition to your computer, boasts only one million subscribers as of December 5, 2005). "The Complete Idiot's Guide[registered] to Skype for PCs" shows what you need, how to download and install the program, and how to make the most of Skype's offerings - both free and paid. Readers will find: how to install and configure Skype; how to use Skype's advanced services, such as video; how to maximize your money using Skype; and how to manage your security and troubleshoot.