Part of this update includes WhatsApp sharing your account information with Facebook to, among other things, provide better targeted ads. There are 98 personal data points that Facebook uses to target ads to you.
What information is being shared with Facebook? The updated WhatsApp FAQ page says that the phone number you used to sign up for WhatsApp with will be shared, as well as the last time you used the service. Facebook will not be able to see your messages, photos or other media you share. And any information that is shared by WhatsApp will not be publicly visible to anyone using Facebook. Meaning, if WhatsApp shares your phone number with Facebook, it won't fill in the phone number field on your profile and make it visible to anyone.
Why is your information being shared?
The FAQ page says sharing your information with Facebook will help the two companies "coordinate more." The claim is that it will help them "fight spam and abuse" more efficiently, as well as -- and this is likely the bigger and more feasible reason -- "improve your experiences within [Facebook] services" through targeted ads.
They say having your number will help them deliver product suggestions from companies "you already work with" versus one you're not familiar with. How your phone number makes this possible isn't exactly clear.
Will I start seeing ads in WhatsApp? No. Well, at least not in the conventional banner ad style. However, WhatsApp is exploring ways to allow businesses to communicate with customers. In the same way that you can interact with your bank via SMS to check account balances or pay your cell phone bill with a text message, WhatsApp wants you to receive information from business, such as receipts for flight information.
The good news is, WhatsApp is (for now) continuing to put you in control. It says, "We do not want you to have a spammy experience; as with all of your messages, you can manage these communications, and we will honor the choices you make." Time will tell if being part of Facebook will alter their stance on this, as well.
Stop WhatsApp from sharing your info with Facebook
Seeing as this goes against WhatsApp's previous policy of never sharing your information with its parent company, this update to the terms is understandably rubbing many the wrong way. Fortunately, you can opt out and remove yourself from the whole situation very easily. Here's how:
The pop-up that appears reads, "If you tap 'Don't Share', you won't be able to change this in the future." And they mean it. After you follow through with this action, the option will no longer be visible from the Account section of Settings and there is no turning back. On the bright side, your account information and app usage won't be shared with Facebook anymore. Though, it doesn't say whether it has already shared your information or whether, if shared, that information will be redacted.