<P> WhatsApp Messenger is a freeware and cross-platform messaging and Voice over IP (VoIP) service . The application allows the sending of text messages and voice calls, as well as video calls, images and other media, documents, and user location . The application runs from a mobile device though it is also accessible from desktop computers; the service uses standard cellular mobile numbers . Originally users could only communicate with other users individually or in groups of individual users, but in September 2017 WhatsApp announced a forthcoming business platform which will enable companies to provide customer service to users at scale . </P> <P> The client was created by WhatsApp Inc., based in Mountain View, California, which was acquired by Facebook in February 2014 for approximately US $19.3 billion . By February 2018, WhatsApp had a user base of over one and a half billion, making it the most popular messaging application at the time . WhatsApp has grown in multiple countries, including Brazil, India, and large parts of Europe . </P> <P> WhatsApp was founded in 2009 by Brian Acton and Jan Koum, both former employees of Yahoo!. After Koum and Acton left Yahoo! in September 2007, the duo traveled to South America to take a break from work . At one point, they applied for jobs at Facebook but were rejected . For the rest of the following years Koum relied on his $400,000 savings from Yahoo! . </P> <P> In January 2009, after purchasing an iPhone and realizing the potential of the app industry on the App Store, Koum started visiting his friend Alex Fishman in West San Jose where the three would discuss "...having statuses next to individual names of the people", but this was not possible without an iPhone developer . Fishman found a Russian developer on RentACoder.com, Igor Solomennikov, and introduced him to Koum . Koum named the app "WhatsApp" to sound like "what's up". On February 24, 2009, he incorporated WhatsApp Inc. in California . However, because early versions of WhatsApp often crashed or got stuck at a particular point, Koum felt like giving up and looking for a new job, upon which Acton encouraged him to wait for a "few more months". </P>

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