The London Olympics may well be remembered as the event that drove home the power of social media — partly to the chagrin but mostly to the benefit of NBC, which controlled images of the games in the United States.

Twitter estimates there were more than 50 million tweets about the Olympics, at a pace of 80,000 per minute after Jamaica's Usain Bolt won the gold medal in the 200-meter sprint. Facebook saw the number of fans of Olympic athletes soar: American gymnast Gabby Douglas had 14,358 followers on July 27 and 540,174 less than two weeks later.

All of the activity pumped up interest in the games. NBC executives privately anticipated the London games would have a smaller audience than the Beijing Olympics of 2008. Instead, the network's prime-time audience averaged 31.1 million people a night through Saturday, up 12 percent from Beijing.

Many factors surely drove interest, like compelling competition and the amount of coverage available on TV and online. Maybe a recession-weary world wanted a collective, uplifting experience. But the explosion of social media is the one big change in the media landscape that would explain the increased ratings, said Lee Rainie, director of the Pew Research Center's Internet and American Life Project.

Facebook had 100 million users four years ago and has 900 million now.

"It was the great unknown," said Mark Lazarus, chairman of NBC Sports. "We believed it would be a positive for us, and people would dialogue about the games even if they knew the outcomes. But every day in social media is a learning experience, not just for us but for every business. Yeah, I think maybe we did underestimate it."

Usage estimates are still coming in, but it appears the U.S. was not alone. The IOC estimates some 900 million people worldwide saw the Olympics opening ceremony. Viewership in Britain was more than the BBC expected. The number of Facebook followers for German gymnast Marcel Nguyen leaped from 7,567 to 179,441 in less than two weeks, according to Wildfire Interactive.

"Sports events are inherently social," said Justin Osofsky, Facebook's director of platform partnerships and operations. "We're never fans alone. We root together, celebrate together and sometimes commiserate together."

NBC announced partnerships with both Facebook and Twitter before the games began. Their tangible impact was somewhat limited — superfluous prime-time segments with Ryan Seacrest — but the intangible impact of increasing visibility for the event is more important. People were more engaged, and watched more as a result, said chief NBC researcher Alan Wurtzel.

One out of five Olympic viewers in the U.S. watched more than one screen at the same time, with tablets or smartphones hooked into the Internet or social media, he said.

Television began as an inherently social activity, since most families could afford only one set and everyone gathered in the living room to watch. But over the years family members retreated to different rooms to watch different TVs. Now, with social media, people are making connections again with others watching the same thing on TV, even if it's someone on the other side of the country or world.

"Cheers" or "Seinfeld" used to be water cooler TV, but series television is now too fragmented. More often, special events like Olympics are filling the desire for shared experiences. Social media often supplements traditional media instead of replacing it, Rainie said.

Social media is big enough that its impact can cut both ways.

People unhappy with NBC found Twitter a communal gathering place, too. The hashtag (hash)nbcfail drew people to complain about issues from NBC's decision not to live stream the opening ceremony (a decision reversed for the closing ceremony) to the airing of Tom Brokaw's one-hour World War II documentary on the penultimate day of competition and the days in between. Twitter and NBC were also both embarrassed when it became public that a newspaper critic's ability to tweet was suspended for posting the email address of an NBC executive.

Many critics focused on NBC's decision to hold back each day's marquee events from television to air them on a tape-delayed basis during prime time.

"Some of the criticism I think was fair and we took note of it and learned from it," Lazarus said, "but I think in general a lot of it came from people who weren't fully aware of all of the things we were doing."

According to a Pew survey, 76 percent of Americans who watched NBC's coverage rated it as excellent or good. Nearly 8 in 10 Americans followed some of the Olympics either on TV or in some other fashion, said the survey, taken Aug. 2-5.

NBC live-streamed every competition through its Olympic website, a process that required customers to prove they were cable or satellite customers, and nearly one in 10 Americans registered devices. After some early glitches, the streams generally ran smoothly. The streams led many Americans to try things they never had before. Three-quarters of people who streamed the Olympics on their tablets had never played video on those devices before; 83 percent had never done it on smartphones, NBC said. It wasn't just young people doing it, either.

There were 63.1 million live video streams downloaded, compared to 14 million in Beijing. The total number of video streams downloaded, live or otherwise, was 154 million, double Beijing. NBC said people spent an average of 30 minutes on its website, up from less than 12 minutes a visit four years ago.

NBC was particularly heartened by the enthusiasm shown by young people in the games. Viewership among teenagers was up 27 percent from Beijing, with girls accounting for most of the gain. For kids aged two to 11, viewership was up 32 percent.

In Britain, the BBC received praise for its Olympics coverage, which included 24 extra digital channels showing live competition. It basically gave TV viewers the ability to program their own Olympics, which NBC only did for computer users. The BBC found that some 88 percent of Britons had watched some of the Olympics on their home turf.

The BBC, however, is a public television network funded largely by a $230 annual fee that television viewers provide while NBC is supported mostly by advertising revenue, and makes most of its money through commercials on its prime-time programming.

NBC actually conducted a few quiet experiments regarding live programming as the games went on. The network had planned to broadcast the gold-medal finals in singles tennis at 9 a.m. in all markets, meaning it would be live on the East Coast and delayed for three hours out West. Instead, the finals were shown live throughout the country. NBC paid a price; its West Coast ratings were only a third of those in the East. A similar approach was taken for the gold medal men's basketball game that the U.S. won. The network ultimately must decide whether consumer goodwill is worth the revenue loss.

One of the biggest surprises for NBC was the large number of people who knew the results of events before the tape-delayed broadcast started, either because media made that news inescapable or they consciously sought the information out. Even more eye-opening was that people who knew the results tended to watch more in prime time, not less.

"People like to see athletes coronated," Lazarus said.

NBC will see time difference issues again during its next Olympics broadcast, in Sochi, Russia, in winter 2014.

"Things are going to be different," Lazarus said. "I don't know how different. We'll take all the lessons from here and apply them. But that does not necessarily mean we will fully change our model."