Jan Koum and Brian Acton co-founded WhatsApp in 2009.
Koum and Acton had previously worked at Yahoo. After leaving the company, Koum developed the idea for a mobile application that could show users' statuses, and WhatsApp was incorporated in California in 2009. The service later evolved into an internet messaging platform.
WhatsApp initially focused on status updates and then became widely used for sending messages, photographs, videos, documents, and voice communications. Its growth was helped by smartphone adoption and by making communication across countries easier through internet connectivity.
Facebook announced an agreement to acquire WhatsApp in 2014. The deal was valued at approximately $19 billion when announced, making it one of the most prominent technology acquisitions connected with a startup. Telegram, Signal, and Viber are separate messaging services founded by different entrepreneurs.