Such a service might sound creepy to the privacy-minded. But it came in handy for Ms. Viator when she arrived Friday at a party in a bar called Speakeasy and could not find anyone she knew. Her friends who also use Foursquare could see where she was, and some joined her a few minutes later.
“I only share my location with people I am comfortable meeting up with, and when I want to be found,” said Ms. Viator, a 26-year-old communications manager at a nonprofit company.
Mobile services like Loopt and Google’s Latitude have promoted the notion of constantly beaming your location to a map that is visible to a network of friends — an idea that is not for everybody.
But now there is a different approach, one that is being popularized by Foursquare.
After firing up the Foursquare application on their phones, users see a list of nearby bars, restaurants and other places, select their location and “check in,” sending an alert to friends using the service.
This model, which may be more attractive than tracking because it gives people more choice in revealing their locations, is gathering speed in the Internet industry. Yelp, the popular site that compiles reviews of restaurants and other businesses, recently added a check-in feature to its cellphone application. And Facebook is expected to take a similar approach when it introduces location features to its 400 million users in coming months.
If checking in goes mainstream, it could give a lift to mobile advertising, which is now just a tiny percentage of overall spending on online ads. If a company was able to pitch offers to people who say they are at a particular spot, it would “allow for the sharpening of mobile advertising,” said Anne Lapkin, an analyst at the research firm Gartner.
The check-in idea got its start in 2004, when Foursquare’s predecessor, a service called Dodgeball, started to let people tell their friends where they were with a text-message blast.
Most cellphones at the time did not have GPS location features, “so using text to check in was a necessity,” said Dennis Crowley, who created the service with a classmate in the Interactive Telecommunications Program at New York University.
In 2005, Mr. Crowley sold Dodgeball to Google, which eventually shut it. He decided to expand on the idea with Foursquare.
“Each time you check in, you’re giving permission to share your location and get pinged with information about interesting things nearby,” Mr. Crowley said.
Since it was introduced at South by Southwest a year ago, Foursquare has swelled to more than 500,000 users. It now has 1.6 million check-ins a week. This year, Foursquare and other location services are the talk of the conference, which has become a launching pad and testing ground for Internet start-up companies.
One of the drawbacks to the check-in model, as opposed to constant tracking, is that people have to remember to use a service, said Josh Williams, co-founder of Gowalla, a location game. Gowalla revolves around finding virtual objects in real-world locations, something like a scavenger hunt.
“Just as people had to get into the habit of tweeting, they’ll have to learn the habit of checking in,” Mr. Williams said.
Many of these services are building in incentives to encourage regular use, often in the form of points and virtual badges.
Gowalla, which says about 100,000 people are using its application, is working with several companies to spread the word about its service at South by Southwest. Users who find a virtual drink coaster can redeem it at a participating bar for a free beverage. And the company teamed up with Palm to offer free cellphones to conference attendees who find a phone icon.
Other services are trying the check-in approach. Hot Potato allows users to create instant chat rooms around locations or events, like a concert. Whrrl hopes to lure users by treating check-ins as keys to exclusive virtual “societies.” And a service called MyTown lets people buy virtual property around them, in a twist on Monopoly.
For Yelp, check-ins are a way to make its users’ reviews more authoritative. Yelp users who check into a restaurant or bar can write a short review from the mobile application and earn points.
“If you go to a business often enough, you get a special badge deeming you a regular of a place,” said Eric Singley, a product manager at Yelp. “It adds an extra layer of credibility to a review online.”
Even Loopt, which since 2006 has relied on a live tracking approach, unveiled a new feature in November called Pulse, which allows users to check into locations to receive tips and suggestions on things to do nearby.
One big hurdle for tracking services like Loopt has been that the iPhone does not allow their applications to keep running in the background for continuous monitoring. Many early-adopter types who might try a new location service are iPhone owners.
But Sam Altman, a co-founder of Loopt, said the check-in model opened up some interesting advertising opportunities. Businesses can offer coupons and specials based on where people check in, he said, as they do with Loopt and Foursquare. “For advertisers, the places you go are much more interesting than the Web sites you click on,” he said.

(from internet)