What is Off-Facebook activity? By default, your Facebook account permit businesses to share information concerning your online activity with Facebook.
Companies that use Facebook's software develop kit, Facebook Pixel (code that helps companies design ad campaigns); and Facebook's other business tools share their users' activity with Facebook. Searches, purchases, and even information on when an app is accessed is shared with Facebook.
Even service providers and marketing agencies used by businesses can feed your data back to Facebook. You can access Off-Facebook Activity in Facebook under settings:
Hundreds of different companies will provide Facebook information about a particular account.
While Off-Facebook Activity can be 'turned off', Facebook will still receive information about your online activity from other businesses.
The information on Off-Facebook activity may appear only several days after it occurs. Facebook does not allow you access to all of the information about your activity that it receives.