SAN FRANCISCO — If you have ever wondered why Facebook showed you that advertisement for a new iPhone game or a cheap flight to Bermuda, you will soon be able to find out.
Facebook announced Thursday that it is going to give its users the ability to see the dossiers of likes and interests it keeps on them, as well as the ability to change, add or delete information in those files. And if you don’t like an ad, you will be able to tell the social network what types of marketing messages you would rather see.
But even as Facebook gives users more control, it is foraging deeper into their activity on other sites.
Right now, Facebook’s dossiers are based mostly on people’s activities on Facebook, such as liking brand pages or sharing a funny ad. But starting next week, the company also will tap data it already collects from people’s smartphones and other websites they visit to hone ad targeting.
Users can opt out of such extended tracking, but they will have to visit a special ad industry website and adjust their smartphone settings to do so.
“At the end of the day, it’s all about data,” said Debra Aho Williamson, who studies social media for the research firm eMarketer and was briefed in advance by Facebook. “Marketers want more data to be able to target people. And Facebook wants more data to make the advertising as relevant as possible.”
For Facebook, giving users more control while digging further into their Internet behavior could be smart business.
A record of user interests gathered by tracking their activity on the site is the basis of ad targeting on the social network. Companies are likely to buy more ads and pay higher prices if they know that their pitches are reaching a receptive audience.
“The thing that we have heard from people is that they want more targeted advertising,” said Brian Boland, Facebook’s vice president in charge of ads product marketing. “The goal is to make it clear to people why they saw the ad.”
Facebook’s move also comes as the Federal Trade Commission and the White House have called upon Congress to pass legislation that would better protect consumers’ private data, including requiring companies to give people more control over the digital files collected on them.
It is unclear how privacy advocates and public officials will react to Facebook’s efforts to provide more clarity about how its ads work. The FTC, which was briefed on the company’s intentions, had no immediate comment. Users will start seeing the changes within the next few weeks.
Although Facebook will now give its users a way to modify the customer profiles that drive the ads they see, users can’t completely get rid of ads. If people were to delete everything Facebook had collected about them, they would simply see generic pitches. Nor is it clear what level of detail a user can control.
Most other big Internet companies, such as Google and Yahoo, already allow consumers to see, change or block some of the personal attributes they use to deliver ads. Last year, the data broker Acxiom also began allowing people to see at least a portion of the profiles it had collected on them.
But Facebook will be the first major Internet company to show consumers how a specific ad for, say, a new television, is linked to a particular assessment of their interests, such as a fondness for electronics.
Every ad will have a tiny arrow in the right corner. If you click on that, then choose “Why am I seeing this?” Facebook will tell you the most important attribute about you that led it to show the ad. You will also be able to click through to your full marketing dossier, or what Facebook calls your ad preferences, and see all of the attributes that Facebook believes describe you, such as “likes video games” or “interested in beach vacations.”
Users can change, delete or add to the information in their files. Facebook executives hope that people will choose to improve the accuracy of the information.
“For some people, they’re going to appreciate that I’m seeing ads for cars because I’m shopping for cars,” said eMarketer’s Ms. Williamson. “And other people will get weirded out by that.”Facebook Inc