Skype
From some of the same developers that wrote KaZaA, Skype is a program for making VoIP (Voice over Internet Protocol) calls to any phone, anywhere in the world. It's free for a Skype user to call another Skype user, regardless of where they are located.
A Skype name is a username, identifying a person's account. It is unique and may include letters, numbers, commas, periods, hyphens, and underscores. The Skype name is between 6 and 32 characters in length and created when first setting up an account.
After logging in to Skype, the Skype name appears in the upper-left corner of the application's window.
On September 12, 2005, eBay acquired Skype for approximately $2.6 billion and on Friday on April 28, 2006, Skype announced that it had over 100 million registered users. Later, on May 10, 2011, Microsoft announced it will purchase Skype from eBay for $8.5 billion in cash.