And like clockwork, after Garland received her champagne, she posted a photo of the bucket of champagne and pair of flutes, with hashtags for the name of the resort and Marriott Rewards, the hotel chain’s points program. Marriott responded with the simple message: “Enjoy! 💍.”

The champagne-senders work at the headquarters of the hotel chain Marriott, less than a half-hour’s drive outside of Washington, DC for a special team called M Live. Quartz was invited to sit in with them one day in December as they monitored social media all day searching for the perfect opportunity to surprise a customer with some free food and beverages—and get positive press for the brand and repeat customers in return.

Social-media posts from the around the world scroll by on one of a dozen screens covering the wall at the rate that’s often more than 1,000 an hour. Yellow dots on a digital map in the center mark the poster’s location. There are clusters in South Africa, Western Europe, Indonesia, and along the coasts of the US and Brazil. Scouring the feeds have their fingers poised, waiting for the perfect moment to engage. They sift through news sites and of course, Reddit, where unsavory content often crops up, such as one topic was on the screen that day was very much NSFW.  During sports events, they keep an eye out for fans cheering at one of their hotels.

They can do this because Marriott, which now has more than 5,700 properties since its merger last year with Starwood, can track guests—or anyone on its property—using what’s known as geofencing technology, which uses GPS or other digital markers to provide a virtual boundary around a certain area. As long as the individual’s account is public, Marriott can see their Instagram, Weibo, and Twitter posts from one of the company’s 30 hotel brands. Facebook accounts are often kept private, Marriott said.

Its staff doesn’t generally field customer complaints or requests for more towels—those are routed to a separate department. M Live’s purpose, in hospitality parlance, is “to surprise and delight.” Which costs ”pennies for the amount of PR” you get, according to Matthew Glick, who heads the M Live centers and joined after working as a producer at networks CBS and NBC.

In another case, a week before, photographer Ashlee Duncan posted a photo of a Marriott in Boston on Instagram and said in the caption that she was bummed that she was eight nights’ short of platinum status for the year, tagging the hotel company. Marriott responded and upgraded her for free and she responded with an effusive thank you—online and for everyone to see. ”They become a brand ambassador for us,” says Glick of such cases.

When asked whether scrolling through their social media might make guests uncomfortable, Marriott said it has “only received positive feedback from our guests” and only looks at accounts that are public.

Not everything works. Marriott keeps a screen of all the trending emojis. Some are good fits, like 🍷 for National Sangria Day, when it may send guests a free cocktail or two. When 💩  was trending, “clearly our brands weren’t going to engage,” says Glick. “Seventy-five percent of the things we identify we don’t do.”

In fact, the day before Garland’s engagement-ring post, a man had just driven a truck into a crowded Christmas market in Berlin, killing a dozen people. The M Live was told to “go dark,” meaning it couldn’t send any special perks like free booze or appetizers to guests, in case it seemed inappropriate. It waited until the 24-hour ban was lifted and sent Garland her bottle of bubbly.

Since opening its first M Live center at its Bethesda headquarters in July 2015, the company has opened one in Florida to work with travelers in Latin America, one in London for Europe, and one in Hong Kong. “Asia Pacific posts a lot of photos,” Glick says. Marriott is planning to open an M Live center in Dubai sometime this year.

Keen to connect with younger travelers beyond individual guests stays, Marriott looks for ways to insert itself into trending social media conversations. When they’re not sifting through social media posts, M Live team members are hatching plans to make Marriott part of stories that have already captivated the public. For example, Marriott sponsored Tom Parson, the human who travels around the world with Lego Backpacker, a Lego man wearing a backpack, and set him up with a free hotel in Seville. Lego Group retweeted the hotel’s post to its more than 420,000 followers.

“I think I saw an article on Bored Panda,” says Glick, about spotting the story about the Lego Backpacker. For the team, it’s much more cost effective than an actual marketing campaign or sponsorship. ”In the time you can figure out how to do a sponsorship, the thing has moved on,” Glick says.

At the height of the Pokemon craze in mid-2016, the company reached out to Nick Johnson, who had just caught all the Pokemon in the US. Marriott put him up in Marriott hotels in Paris, Hong Kong, and Sydney to continue his quest.

Johnson, of course, mentioned the hotel in a post.

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