I get buy with a little help from my friends…
The so-called social-context ads, which Facebook started rolling out over a year ago, are based on data it collects on the likes and friends of its users. The ads appear on the right side of a user's homepage, with an image and headline from the advertiser. With the ads are the names of any of the user's friends who have clicked on a button indicating they like the brand or ad. The user is also offered a chance to indicate he likes the ad.
Facebook says the people whose names it picks to feature in the ads have voluntarily indicated they like a brand, and it shares their names only with those they have identified as friends. Still, some users may not realize that clicking a button to indicate they like a brand gives Facebook permission to use their names when the site shows an ad from that brand to their friends.