Facebook knows a lot about you based on your time on its site — your age, your gender, where your work, your interests — and it uses that information to help companies sell you things.

Facebook said this week that it will soon begin using the data it collects on your use of the “like” and “share” buttons and other social widgets embedded in millions of websites and apps to better personalize the ads it shows you, starting next month.

That’s in addition to the information Facebook already puts towards ads, such as your web-surfing habits, your profile details and your activity inside its digital walls.

“We hope that the ads people see will continue to become more useful and relevant and that this new control will make it easier for people to have the ads experience they want,” wrote Stephen Deadman, Facebook’s global deputy chief privacy officer, in a blog post.

If you assumed that Facebook was already doing this, it may be because the company first announced the undertaking more than a year ago and has been busily stockpiling information on your web-surfing habits for years in anticipation.

Not to mention that it’s generally a safe bet that any public interaction with a Facebook product will be tallied away for advertising purposes.

A Facebook spokesperson is quick to point out that the data collection is no different than the trackers most major websites employ to trace their visitors’ web habits.

Frustration with these hidden functions is a driving force behind the surging popularity of ad blocking software.

If you’re uncomfortable with Facebook’s hyper-targeting, the good news is that you can opt out of the ads based on website or apps visits on the settings page under the “ads” tab.

There’s also a panel where you can view and edit the profile of interests that Facebook uses to target your ads.

The Facebook opt-out option does not stop Facebook from still collecting this data.

Putting an end to that would require a service like Ghostery that shields your browser from hidden trackers.