The immense growth of a million users a day for the fast-growing WhatsApp messaging service has called the attention of Facebook. Its popularity has passed Twitter. Currently, WhatsApp has over 450 million monthly users. This was more than enough for Mark Zuckerberg and friends at Facebook to plan to acquire WhatsApp for $19 billion. That amount is much more than the $3 billion offer Facebook wanted for Snapchat. WhatsApp, formed by a team of 55 employees, will become a subsidiary of Facebook.
According to a post on Zuckerberg’s profile:
WhatsApp will continue to operate independently within Facebook. The product roadmap will remain unchanged and the team is going to stay in Mountain View. Over the next few years, we’re going to work hard to help WhatsApp grow and connect the whole world. We also expect that WhatsApp will add to our efforts forInternet.org, our partnership to make basic internet services affordable for everyone.
So, what does this acquisition of WhatsApp means for Facebook? An amount of daily users close to half a billion that could reach a billion as well and more than the amount of people using other communication apps combined.

[Source]: Facebook: Facebook to Acquire WhatsApp [https://investor.fb.com/common/download/download.cfm?companyid=AMDA-NJ5DZ&fileid=727110&filekey=3b516115-909d-4044-b758-d1742a46a135&filename=Facebook_02_19_14.pdf]; Zuck @ Facebook: [https://www.facebook.com/zuck/posts/10101272463589561?stream_ref=1].