Facebook Tracks Your Online Activity: How to opt out 

Facebook tracks your online activity through various methods, such as cookies, social plug-ins, and pixels, to show you personalized ads.

You can view and clear your off-Facebook activity, which is the information that Facebook receives from other websites and apps that use its services.

To access your off-Facebook activity, go to Settings & Privacy > Settings > Your Facebook Information >Off-Facebook Activity.

To stop Facebook from tracking your future off-Facebook activity, click on More Options >Manage Future Activity and turn off the feature.

You can also change your ad preferences, disable ad tracking at the device level, clear your activity log, turn off location tracking, and use an anti-tracking extension to limit Facebook's tracking.