Viber is an increasingly popular instant messenger, competing with Skype and WhatsApp. Users can send text messages, share photos, and make voice and video calls. The application is based on the VoIP protocol and was created as a free alternative to the standard methods of communication using mobile phones or smartphones.

It has a simple and clear graphical interface, allowing the user to make text, voice or video calls. Viber was created in 2010 and in the initial phase was available only for iPhones. It currently has more than 200 million users worldwide and is available for Windows and Mac OS, Android, BlackBerry OS, iOS, Symbian, Bad and Windows Phone.

Using a messenger is very similar to using a standard phone. Calls between users are not made using account names (such as in Skype) and real phone numbers that were used when creating and activating your own profile. For example, using Viber we can communicate according to the computer-computer, computer-telephone, phone-telephone schemes, and all that is required is an Internet connection (e.g.

WiFi or 3G). The application is able to synchronize the transferred content between the mobile and desktop version.