Whatsapp is an instant messaging application for mobile phones which is widely used by consumers in many parts of the world. Whatsapp is also popular in Switzerland, and widespread use of the app has contributed to the decline in the use of SMS messaging. Whatsapp Inc., the applications publisher, was acquired by Facebook Inc. in 2014.
Whatsapp lets users read and write short messages, and transfer digital images, videos and voice messages. Users can also make VoIP calls using Whatsapp.
Unlike SMS messages, messages sent vie Whatsapp are not transferred from one device to another by one or more telecom service providers. Instead, they are simply transferred over the Internet using data connectivity provided by third-party service providers. For this reason, Whatsapp and similar services are referred to as over the top (OTT) services.