A Google search for “boy bands back” results in a long list of headlines.

“Boy bands are back, wholesome or sexy” reads one posted at The New York Times site.

At the Los Angeles Times: “A new crush of boy bands.” The Seattle Post Intelligencer: “The boys are back, and so are their bands.”

Talk of a boy band revival starts with the British quintet One Direction, which emerged in 2010 from the British version of “The X Factor,” a talent search that, unlike “American Idol,” allows vocal groups to compete. The 18- to 20-year-olds placed third on the show, but the group was subsequently signed to a recording deal by Simon Cowell, the show’s creator and a judge. He has since launched an American version of “The X Factor.”

In November 2011, One Direction released “Up All Night,” its debut album. On the strength of its single “What Makes You Beautiful,” the album became the first by a British group to debut atop the Billboard 200 chart, a feat that eluded even the Beatles. The album has since gone gold, according to Billboard magazine.

The band recently announced its 2012-13 world tour. It stops July 19, 2013, at the Sprint Center. About a year away, and the show is almost sold out.

The other boy band making big waves is the quartet Big Time Rush, a live act spun off the Nickelodeon television network’s show of the same name. The four portray hockey players from Minnesota who live in Hollywood, trying to start a life in the music industry as, naturally, a boy band.

The group has released two albums since 2010, one of which has gone gold. Big Time Rush headlines a show at the Sprint Center on Friday. Tickets are still available.

Other big players include the Wanted, another British ensemble making waves on U.S. charts, and Mindless Behavior, a four-piece R&B/hip-hop vocal group from Los Angeles.

Observers say those acts are just part of a larger class of boy bands, the popularity of which has risen over the past year or two with dramatic speed.

“The fans’ passion is there much earlier than it used to be,” Ernest Martinez, an on-air personality (Ernie D) and creative director at Radio Disney, told The Star. “Fans have way more access to bands and music than they used to.”

Bill Rusch, who has been an independent record promoter, said, “I’ve been doing this for 35 years, and I’ve never seen what’s going on right now. The One Direction tour is selling out arenas a year in advance. It’s unheard of. And it’s not just them.”

And this club is not for boys only. Rusch is working with the Korean group Wonder Girls, a group introduced to America in 2009, when it opened for that year’s reigning boy band, the Jonas Brothers. Wonder Girls also opened for Justin Bieber, the reigning teen sensation. The Girls are about to jump full steam into a multimedia campaign.

“There is going to be a Wonder Girls movie out in October,” Rusch said, “and Nickelodeon is shooting 20 episodes of a 30-minute Wonder Girls sitcom.”

What’s behind the explosion? Rusch said it’s obvious: a demand for the music and social media.

“It’s so much easier for kids to share music and to get momentum going,” he said. “Acts can blow up so much faster now.”

Add in a television connection, whether a talent show like “X Factor” or a sitcom, and the viral connection is even more potent.

“It can happen so fast it catches parents by surprise,” Rusch said. “We get calls from moms and dads who are trying to figure out the One Direction buzz. They’re selling out arenas, and parents don’t know enough about them, whether they’re wholesome enough for tweens.”

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For decades preteen and adolescent girls have been falling in love with cute boys in bands and their shiny, poppy love songs — at least since the mid-1960s. Most were inspired by Beatlemania. Some were manufactured; others were slightly more legitimate: the Monkees, Paul Revere & the Raiders, Herman’s Hermits, Dino, Desi & Billy, the Jackson 5, the Osmonds.

In the ensuing decades, radio and the music charts were filled with pop hits from all-boy vocal ensembles with slick dance moves or heartthrob bands that played instruments: New Edition, Menudo, New Kids on the Block, Color Me Badd, Boyz II Men, Hanson, Westlife, 98 Degrees.

Music is cyclical and styles come and go, and so do the boy bands. But their cycle has been somewhat predictable. Bands get popular, put out two or three albums and tour. But the boys get older and eventually have to quit. No one wants to watch 28-year-old men sing puppy-love songs to teenage girls. The girls in the audience also grow up, move on to other music, and the cycle runs its course.

But it doesn’t completely disappear. Something is typically waiting in the wings. Martinez said it appears that 16-year-old Ross Lynch already is being groomed to become the next Bieber, who is still only 18 but is starting to navigate the career path to adulthood.

“Every generation has their boy bands or their Justin Bieber,” Martinez said. “There’s always something coming next.”

That was the case in the early to mid-1990s, years that were known predominantly as the grunge era.

But one of the biggest boy-band eras ever was already under way. In 1992, about the time New Kids were calling it quits, Lou Perlman started auditions for the group that would become the Backstreet Boys; three years later he created ’N Sync. By 1998, they were the two biggest acts in pop music.

Sales of each group’s first three albums in the United States alone were skyscraping, even by the old standards. In 1998-2000, the Backstreet Boys’ first three albums sold 35 million copies combined; in 1998-2001, ’N Sync’s topped 26 million. Each group also toured the world several times, selling out arenas and stadiums.

In this free download/Spotify/iTunes era, those kinds of music sales are out of reach. Eight months after its release, sales of One Direction’s “Up All Night” are still short of 1 million. And though they can generate enthusiasm and hype much quicker, it remains to be seen if today’s bands will be as enduring as some of their predecessors.

A reunited New Kids on the Block has performed twice at the Sprint Center over the past few years, including a co-headlining show with the Backstreet Boys in 2011. This year, New Edition headlined a show at the arena.

For the new bands, the race is about starting the buzz and milking it, which means working the social media outlets relentlessly.

It took the Backstreet Boys and ’N Sync several years to generate the hype that turned into sold-out crowds and multiplatinum albums. Both started in smaller venues, including shows at Memorial Hall in Kansas City, Kan., before graduating to the big venues. Neither, like One Direction, sold out arenas on its debut U.S. tour.

Martinez, whose station’s audience is young children and teenagers and everyone in between, said the band who first used that system to its advantage was the Jonas Brothers, who, like Big Time Rush, starred in a television series.

“They worked it all, Twitter, Facebook, YouTube, to get more connected with their fans,” he said. “Since then, things have gotten even faster and more immediate.”

One Direction and its label, Columbia Records, launched a social media campaign that created demand before its album was released. According to the New York Times, the campaign increased the band’s population of Facebook friends from 40,000 to 400,000. When the album was released, fans called radio stations requesting “Beautiful,” and some programmers were caught off guard.

Justin Wright, who managed the Backstreet Boys, ’N Sync and the New Kids, told the Times, “(Kids) are calling the radio station, and the radio station is scratching its head, saying, ‘We don’t even have that record yet.’ It’s almost like the Beatles. I call it hype but it’s positive hype. Because it’s all real.”

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That kind of hype has been building for Wonder Girls, too, Rusch said. The five-member girl group is part of the world of K-pop — Korean pop — an industry that concocts an endless stream of teen-idol bands.

K-pop showcases sold out the Staples Center in Los Angeles this year and Madison Square Garden in New York for the third year in a row, Rusch said, “and with no radio to back it up.”

The plan for Wonder Girls, he said, is to bombard the Korean communities in the United States with radio and social media to generate some of that real, positive hype. There are signs the campaign already has traction.

Wonder Girls shot a $650,000 video for their single “Like Money,” featuring rapper Akon. On July 9, with moderate fanfare, the video was posted. Within 10 days, it was approaching 3 million YouTube views.

The group also will pair up with radio stations to get its single played, but not in traditional ways.

“The incentive for programmers used to be to get their ratings up. Now the incentives are changing. It’s to get your (Web) page views up and increase the size of your Facebook friends list. So artists like Wonder Girls are giving stations access to exclusive content for their Web and Facebook pages,” Rusch said.

Does this high-speed worldwide glut of teen-idol bands mean the market will eventually recoil? Rusch thinks not. The market is big and growing, and demand, especially for something new, is almost insatiable.

“There are so many more ways to reach this market,” he said. “You have the Disney Channel, Nickelodeon and other kids’ networks. There may be a glut of these kinds of bands, but there are more ways to share what they do and a big audience for it. I have to think it’s going to keep going for a while.”

In other words, the boy bands may be back, and it doesn’t look like they’ll be going away for a while.