This one cuts both ways, at least from a consumer perspective: Facebook is simultaneously making it easier for users to control what ads it shows them and harder for ad blockers to work on its site.
The new ad preferences let people tell Facebook not to serve them ads from particular companies that may be targeting them. If a consumer is on a brand's email list, for example, she can prevent the brand from using her email to find her on Facebook. Facebook's preferences will now show users the advertisers that have them on email lists, and present them with the option to stop receiving ads from those brands.
Email targeting has become one of Facebook's most effective methods of connecting brands with customers.
Facebook users can also use the company's settings to more precisely fine-tune the ads they see. The revamped system gives the users more control to check boxes that prevent ads based on interests such as travel or cats, Facebook said.
"People can modify the interest we use to show them ads to make them more relevant to their interests," said Andrew Bosworth, VP-ads and business platform, Facebook.
The changes benefit the marketers, too, according to Mr. Bosworth. "Advertisers want to make sure they're spending money in a way they think will be effective for them."
At the same time, Facebook is introducing an initiative that it says thwarts ad blockers' attempts to discern sponsored posts from non-sponsored posts. Previously, Facebook was just as susceptible to ad-blockers on its desktop site as any other publisher.
"It will be really hard for ad-blockers to distinguish what is an ad and what is not an ad," Mr. Bosworth said.
Ad-blocking has become an industry scourge, with more people installing the easy-to-use software. Although many people predict that technological countermeasures will eventually fail as ad blockers engage in an arms race with publishers, Facebook said it was not concerned that ad-blockers would evolve to beat its new measures.
"If people really want to block ads they would have to do a deep inspection of the content, which would be really slow," Mr. Bosworth said. "People who have the choice of seeing ads on Facebook and a slower experience would all choose to see the ad."
Still, plenty of people are choosing not to see ads. The Interactive Advertising Bureau has reported that a quarter of internet users deploy ad blockers on desktop.
The practice hurts already struggling publishers, which have been coming up with creative ways to convince readers to whitelist their ads to circumvent ad-blockers.
Adblock Plus, which claims 100 million users, maintains an "acceptable ads" program that approves certain styles of ads and charges larger publishers to participate.
It's a troubling model, Mr. Bosworth said. "They take money for letting ads get through," Mr. Bosworth said. "There's a degree of moral hazard to that."
Facebook's ability to counter ad-blockers makes it even more dominant in the marketplace competing with publishers for ad dollars, according to Frédéric Montagnon, CEO of Secret Media, which works with the industry on anti-ad block strategies.
"Buyers are buying more and more on Facebook because they start to understand they are not losing reach to ad block on Facebook," Mr. Montagnon said by e-mail. "While they know they are not able to reach a significant part of the user they want to target everywhere else."
Facebook said it's deploying the ad-block counter measures because it feels they interrupt the full experience it delivers users, arguing that users are just as interested in ads targeted to their tastes as they are content tuned to their likes. Presumably, however, consumers trying to block ads when they visit Facebook have come to a different conclusion.
While there is clearly financial incentive to defeat ad blockers, most of Facebook's revenue comes from its mobile app, where ad blockers are not a factor.
Anytime a new technology tries to thwart them, the ad-block software community finds a way to defeat it, according to Till Faida, CEO of Eyeo, the software-maker behind Adblock Plus. "Cat and mouse games are a waste of time," Mr. Faida said. "At the end of the day user choice will prevail on the web."
Adblock Plus advocates for publishers to adopt "acceptable" ads.
"It makes more sense than forcing ads on users they clearly don't want to see," Mr. Faida said.
CORRECTION: An earlier version of this article erroneously referred to Facebook's VP-ads and business platform as Adam Bosworth. His first name is Andrew.