Google and Facebook are sort of rivals, even if the average Joe may not realize it. They're both heavily invested in the race to know everything about you and to use that knowledge to make lots of money...somehow. And while Google has become a pretty integral part of using the web, on mobile it is important that searches don't just take you to websites, but apps too. That's why today's announcement via an Alphabet spokesperson that Google will show mobile search results that link to the Facebook app is important.
Now, Google has always tried to index Facebook. You have probably seen Facebook profiles and pages in Google search results before. Indexing the app is more about deep linking than anything else. Google will also not have access to any information that is only accessible to your logged-in Facebook account, which restricts the intelligent capabilities of search results.
On the other hand, there's no reason for Facebook to make that valuable information available to Google and probably no reason you should feel comfortable having those two data troves intermingling.
Nonetheless, Facebook didn't have to cooperate, but decided to make the web a little bit easier to use for all of us. Google has to solve the challenge of finding information within apps rather than just the world wide web more generally, which will in many cases take cooperation from big shots like Facebook.
- Wall Street Journal