(Facebook)
If you use Facebook, then you know the deal.
Facebook is free to use and fun, and sometimes necessary if you belong to groups that use it to communicate with their members.
But in exchange for that service, you have allowed it to track your activity so that advertisers can find you, hopefully to show you stuff you'll want to buy.
In other words: you can't opt out of ads on Facebook without opting out of Facebook itself.
But there's still a lot you can do to control the ads you see.
And there's also stuff you can do to stop Facebook from watching what you do on the rest of the internet in service of its advertisers.
Besides all the usual arguments about privacy, there is another good reason to figure out what Facebook knows about you and participate in that. It shows you ads based on what it thinks you like. The better it does this, the more likely you are going to see ads on things that truly interest you.
Facebook has three ways to figure you out.
1. What you tell it directly (name, age, marital status, parental status, where you live, work, went to school, etc.).
2. What you do while you are on Facebook, including stuff you've "liked," groups you joined, photos and links you've shared, things you click on.
3. What you do on the rest of the internet outside of Facebook such as websites you visit. Many sites track this information via cookies (and similar technologies) and Facebook reads those cookies and uses that information to serve up ads both on its site and on other websites, it says.
It's easy to see the things you've directly shared with Facebook (and your friends) on your Timeline profile page. But to see a fully tally of what Facebook thinks you like, you need to find a tool called Ad Preferences.
This tool is not easy to find. (Facebook has published a slideshow that explains how.)
Locate it by using the controls Facebook has embedded into the ads themselves.
Head to your Facebook news feed.
Hover your mouse over any ad you see in the right-hand column and look for the little "x" to appear in the corner of the add. Click on it.
(Facebook screen capture)
Alternatively, look for an ad in your news stream, and look for a little arrow. Click on it.
(Facebook)
Then look for "Why am I seeing this?" Click on it.
(Facebook)
That's where you'll find the link to the Ad Preferences page. From here you can tell Facebook to stop showing you ads from a particular advertiser.
That doesn't mean that Facebook will stop showing you ads, or limit them. In fact, Facebook says, "This won’t change how many ads you see. but, because we’ll know more about what you like, they should be more relevant."