Beck wins the Grammy Award for Album of the Year, Missy Elliott plays the Super Bowl halftime show, and Suge Knight is up to no good. The cool kids are wearing crop tops and Doc Martens, gas is two bucks a gallon, a Clinton or a Bush may be headed for the White House—and Salt-N-Pepa's here!

Which decade is this again?

Yes, the '90s are back, as confirmed by virtually every social documentarian in every forum from The New York Times to Cosmopolitan to NPR. The period that gave us the fanny pack, the Furby and the Macarena and that writer Kurt Andersen recently dubbed "simply the happiest decade of our American lifetimes" has come back in force, spilling into entertainment, fashion, food and more. While elements of '90s nostalgia have popped up in the zeitgeist for years, at no other time have beloved relics of the era, from the scrunchie to the Spin Doctors to Crispy M&M's, been so much a center of the culture.

The '90s are so au courant that BuzzFeed recently published "17 Times the '90s Already Came Back in 2015"—among them, all the episodes of Friends hitting Netflix, Courtney Love guest starring on the Fox series Empire and previously unreleased Spice Girls tracks being leaked online. A '90s nostalgia board on Pinterest—with snaps of a young Justin Timberlake and a Teen People cover featuring Mary-Kate and Ashley Olsen—has more than 100,000 followers.

Why all this now?

It's been observed that it takes around 20 years for us to come to view some moment in the past with sentimental longing (like, say, the '70s were to the '90s, or the '50s were to the '70s). But our affinity for the decade that brought us the Internet, the compact disc and Viagra may be deeper than mere timing.

Millennials are wistful for that time when our pre-9/11, pre-Great Recession, pre-24/7 cyberconnected world seemed a lot less threatening and a lot more fun, observes Maude Standish, a trend forecaster and director of strategy at the Los Angeles ad agency Mistress.

Adds Jane Buckingham, CEO of trend forecasting and media firm Trendera: "It's the first time that millennials have started recycling their childhood, and the '90s are their point of reference. But it's taken on mass appeal now, and it may have more staying power as a trend than we think."

But the trend extends far beyond millennials. Members of so-called Gen Z—those born in this century—have latched onto the '90s because they identify with its more rebellious, individualistic icons (think Kurt Cobain and Nirvana).

And for their part, people in their 30s—a group famous for its reluctance to embrace commitment and the responsibilities of life, earning it the label "the Peter Pan generation"—find their own comfort in the period. "They're afraid of growing up fully," explains Standish (who counts herself among this group), "so they're reaching for the equivalent of a security blanket."

"People want to recapture that innocence, that sense of optimism, the feeling of security we had in the '90s," adds Emily Fox, executive producer of the new VH1 dramedy Hindsight, which is set in the mid-'90s. "We're looking over our shoulders at a golden age that gets more golden as time goes by."

Marketers are tapping this back-to-the-'90s trend in a big way.

One of the most talked-about ads of the year—for Calvin Klein underwear, featuring a tatted-up and, if Internet chatter is to be believed, manhood-enhanced Justin Bieber—recalls "Marky Mark" Wahlberg's legendary, crotch-grabbing promotion for the brand in the '90s. Current print ads heralding the return of Reebok's Ventilator sneaker, which first hit the market in 1990, are dizzy with '90s imagery, as are ad campaigns and product lines from the likes of DKNY, Marc by Marc Jacobs and Versace.

Oreo's recent Valentine's Day-centered campaign for a limited-edition Red Velvet variety was supported by six digital spots inspired by MTV animated series of the '90s, like the deadpan Daria.

And for its spot "Every '90s Commercial Ever," digital studio Rocket Jump gathered up assorted tropes from Saturday morning commercials of the decade and twisted them into a campy horror-comedy ad for a nonexistent juice drink. Drawing comparisons to Adult Swim's viral video "Too Many Cooks," the fake ad snagged more than 4 million YouTube views after it hit this month. And last summer, Wendy's brought back its pretzel bun for the first time in a decade, supported by a campaign featuring the music of '90s acts like Boyz II Men and Jon Secada.

Then there's the 1988 breakout track that set the stage for one of the '90s biggest acts, and thanks to Geico, it's stuck in our heads all over again.

Geico and The Martin Agency hit marketing gold when they appropriated "Push It"—the signature song of one of the most iconic music acts of the '90s, the Queens, N.Y.-based hip-hop trio Salt-N-Pepa (that would be Cheryl "Salt" James Wray, Sandra "Pepa" Denton and Deidra "DJ Spinderella" Roper)—for a TV spot that broke last December and went on to air in this year's Super Bowl. (It's also been viewed some 6 million times on YouTube.) In the irresistibly entertaining (and admittedly very silly) 30-second ad, Salt-N-Pepa urges assorted everyday people—a football team in training, a pregnant woman—to "push it, push it real good." (What does it have to do with car insurance? What does any Geico ad have to do with car insurance?)

Photo: Mary Ellen Matthews; Styling: Ise White; Hair: Damian Monzillo for Artmix Creative using Davines; Makeup: Sophie Haig

Executives at The Martin Agency say they wanted to be cheeky and yet not treat Salt-N-Pepa like some novelty act returned from the dead. "We're not spoofing Salt-N-Pepa—we're celebrating them," explains Ken Marcus, senior copywriter. "The spot's meant to be funny, but the band isn't a punch line."

Two years before Salt-N-Pepa started pitching insurance, another timeless throwback, Sir Mix-a-Lot's "Baby Got Back," was heard in a spot for Charmin toilet paper. Burger King and Butterfinger have also used the number in their spots.

"We all seem to remember it so warmly," Hindsight executive producer Fox says of the '90s. "It was blissful."

The premise of VH1's 10-episode series—which liberally sprinkles in period-perfect artifacts like the flying toaster screen saver, mix tapes and clogs—did not require that it be set in the '90s, she explains. But she was drawn to the decade, she says, because it is rich with storytelling opportunities—not to mention that a trove of '90s-era props are available on eBay.

And anyway, the network was ahead of the '90s rewind by a full decade, premiering its look-back miniseries I Love the '90s, in which celebrities like Jerry Springer and MC Hammer waxed poetic about the decade, way back in July 2004.

Nostalgia has always been a mainstay for VH1, notes network president Tom Calderone, offering that the '90s hold up better than most decades, "not like a Flock of Seagulls hairdo." The channel—home to reality shows about Salt-N-Pepa and Backstreet Boys' Nick Carter, as well as a hit biopic about hip-hop group TLC—was drawn to scripted series Hindsight precisely because it is "not a one-note gag about the '90s," Calderone says. "It doesn't beat you over the head with, ha, ha, giant cellphones and VHS tapes. The '90s becomes a personality in this show, and that's a real sweet spot for us. Most of our audience grew up with [the daily MTV show] TRL as their town hall."

When it comes to ad-supported entertainment, Hindsight is hardly alone in jumping on the '90s wave. Fox reportedly may exhume The X-Files, while FX is prepping American Crime Story, a miniseries about the O.J. Simpson trial. ABC's buzzy midseason comedy Fresh Off the Boat has mid-'90s central Florida as a backdrop, while Syfy did a refresh of '90s flick 12 Monkeys. The National Geographic Channel last summer rolled out a three-part documentary series dubbed "The '90s: The Last Great Decade?"

Tonight Show host Jimmy Fallon, the millennials' own Johnny Carson, paid homage to Saved by the Bell with a recent reunion of the cast of the '90s sitcom. This, after he had already reshot the opening credits sequence of the Will Smith sitcom, The Fresh Prince of Bel-Air.

(The rebranded TV Guide Network, now called Pop, recently debuted with a focus on '80s and '90s culture, with the informal tagline "What Would Jimmy Fallon Do?")

Elsewhere on the tube, those adorable crime fighters the Powerpuff Girls got a Cartoon Network special. Girl Meets World—a sequel to '90s hit Boy Meets World—was renewed for a second season by Disney Channel.

And finally, Showtime has plans to reprise quirky, cult-favorite '90s murder mystery Twin Peaks.

So, who knows? Maybe the best thing about everything old being new again will turn out to be that we'll finally find out what the series' Laura Palmer meant when she said, "I'll see you again in 25 years."