So what do you “like?” From favorite photos to favorite brands, Facebook users have become obsessed with the like button and are reaping the benefits- from discounts to contest wins to inside information about their favorite brands. But beware, because experts say there’s more to the like button than first meets the eye.

Annie Pace Scranton and her friend, Chris Crater, both love Facebook. When it comes to the like button, they have very different tastes.

“My like is hard to get. When I like, I want it to really mean something,” says Chris Carter.

“And I would say that I like things probably about once an hour. Is that too much?” asks Scranton.

Not for advertisers, who have embraced Facebook in a big way. Hundreds of thousands have created pages for their products, hoping to grow their number of likes.

“Liking has become the 21st century bumper sticker. It’s kind of your way to show your identity and say, ‘Hey I like this brand,” says Bart Steiner.

Steiner, the CEO of marketing firm Bulbstorm, says companies recognize the power of the thumbs up knowing it grows their list of potential customers, and they’re willing to offer big rewards to those who like them.

“Virtually every brand that’s been on Facebook for a while has done some kind of sweepstakes,” says Steiner.

From luxury vacations, to fine jewelry, to high-tech electronics, “like” something on Facebook and you can win. but, that’s only the beginning of the benefits.

“Offers, discounts, or access to unique information. Or you can give your feedback to a brand for the first time and have them really be able to listen to it,” says Steiner.

You may want to think twice before you click. Experts say there are also potential drawbacks.

“Consumer beware, when you like a brand, you might be used as part of an advertising campaign,” says Steiner.

Your support may show up in a brand-sponsored ad for all your friends to see. Facebook is even stepping it up with a new product called Sponsored Stories where not only your name, but your picture, will show up on top of an ad.

“The data shows that very often those can be two or more times as effective as an advertising medium. Because by putting my likeness there, they’ve essentially given my endorsement,” says Craig Spiezle.

Spiezle, of the Online Trust Alliance, says you should also be concerned with privacy issues. A lot of these likes are connected to apps that ask you for personal information in order to enter a sweepstakes, get a special deal, or more.

“How is that data being used? How can you delete it? How long is it kept? And perhaps one of the most important things, who’s it shared with?” asks Spiezle.

Read privacy policies and check your own privacy settings, too.

“They may not be set or optimized for privacy settings by default,” says Spiezle.

Facebook says it respects customer privacy. While you can’t opt-out of the Sponsored Stories ad campaign altogether, you can check your Facebook activity log to make sure you’re only sharing these ads with people you want to.