Explanation

WhatsApp allows users to send text, voice messages and video messages, make voice and video calls, and share images, documents, user locations, and other content. 

Initial release date: November 2009

Original authors: Brian Acton, Jan Koum

Yahoo was founded by Jerry Yang and David Filo in January 1994 and was incorporated on March 2, 1995.

Founded: January 1994

Headquarters: Sunnyvale, California, United States

Gmail is a free email service provided by Google.

Date launched: April 1, 2004

Created by: Paul Buchheit