WhatsApp

Just like any other messaging app, WhatsApp features all the regular features that you would expect. It allows users to send media files as well, including images, videos, and sound files. All of these multimedia messages are highly compressed so that they use the least amount of Internet traffic available.
 
The application also comes with support for group chats or family chats, not to mention the fact that it can be used to place calls as well to other people that have WhatsApp installed. This particular feature uses a lot of Internet data, so if you intend to place calls with WhatsApp you should do it over a Wi-fi connection.