Skype is a computer program that offers a VoIP ('Voice over Internet Protocol') service. This lets you make calls to people all over the world via your computers or telephone and have text chats. Calls between computers are usually free, and other Skype calls are generally inexpensive.
With more than 650 million registered users, Skype is by far the most popular VoIP service, and 'skyping' is now almost as familiar a term as 'googling'.
Video calls, phone calls and chat
Skype can connect to a webcam (a small camera that may be built into your computer screen or can be bought separately). This means that you can make free video calls to anyone in the world as long as they have the same equipment and a Skype account.
You can also connect to traditional phone networks through Skype, then call any phone number on Earth from your computer. The price is usually far below average – especially for international calls. Text chats are free.
You can install an app (small computer program) on to a smartphone that lets you connect to your Skype account. That way, you can make calls for free from your phone while on the move (though you may need to use wifi for this feature).
Skype is free to sign up for and download, and any costs can be dealt with on a 'pay as you go' basis, with no line rental. Subscriptions for frequent callers are available, however, as is a premium version that allows you to make group video calls.
Alex Duin is a freelance writer specialising in technology.