NEW YORK - If you??re not sure what Foursquare is all about, just ask the next college student who passes by. And like Facebook and Twitter, the location-based social media network is becoming increasingly popular with marketers.

In a nutshell, and according to Wikipedia, Foursquare is a Web and mobile application that allows registered users to connect with friends and update their location. Points are awarded for "checking in" at venues. Users can choose to have their Facebook and/or their Twitter accounts updated when they check in.

Although a relatively small social networking tool with about one million users, companies like PepsiCo are eyeing Foursquare to "sell its customers sodas whether they are near a grocery store, a restaurant or a gas station," writes The New York Times. Thanks to a new partnership, PepsiCo can incorporate its loyalty program into the Foursquare network, which gives PepsiCo "a live notification when its customers are close to those sites, and can present offers that get them into the stores."

B. Bonin Bough, director of social and emerging media for PepsiCo, told the newspaper: that being able to drive foot traffic into stores "is a huge opportunity, because that??s where our product is sold...Ten blocks mean a lot."

In fact, Foursquare can turn a smartphone into a virtual loyalty card program.

"It gives us immediate feedback for what??s going on in the marketplace," Margery Schelling, CMO of PepsiCo Foodservice, told the newspaper. "That??s invaluable."

The "real appeal" for retailers, meanwhile, is the ability for Foursquare to tell them exactly where their loyal customers are, when and where they are "checking in" to nearby locations, and give them the ability to offer discounts or specials on merchandise. This data, notes the newspaper, can be used to learn more about store traffic and when a retailer??s most loyal customers are visiting the store.

"If you check into work, then you leave work, you check into a bank and then you check into a store, that??s a behavior that, in aggregate, we might use to transform the way we market to you in the offline world," Bough told the newspaper. "We might see dayparts that are more likely for you to check out of some place and go to the store, and we might do advertising during that specific daypart in that specific place."

In March, Foursquare added a tool that allows businesses to see who is checking into their locations, including the amount of check-ins, the male-to-female ratio, how many times they frequent a location and when.

Pepsi??s Foursquare program will kick off in June. Bough told the newspaper that he expects that when a Foursquare user is near a Pepsi retailer, "an offer to enroll the person in a Pepsi rewards system will appear. Once people are enrolled, whenever they check in at a grocery store or drugstore selling Pepsi, they will accumulate rewards points or badges that they can redeem for products or offers or donate toward charities."