Seems like the whole world is 'Happy'

Pharrell Williams' impeccable style and boyish good looks -- as seen here at the 2014 Elle Style Awards in February -- have convinced the Internet that he's secretly a vampire. He's not, obviously, but we understand why many can't believe that this 40-year-old superstar looks so young. Take a look back at Pharrell through the years and see if you can spot any aging:

Here's Pharrell on the right with his band N.E.R.D. in August 2002. The producer/singer/songwriter's hats have gotten bigger, but his face has stayed the same.

We know it's hard to tell, but Pharrell Williams, left, and rapper Bow Wow, center, actually aren't the same age. When this photo was taken in August 2003, Williams was 30 and Bow Wow was 16. (That's Williams' musical partner in crime, Chad Hugo of their production group The Neptunes, on the right.)

By 2004, Pharrell had been outed as the music industry's go-to guy for a chart-topping hit. But even with the increased visibility and work, do you see a stress wrinkle on this guy's face? Because we don't.

Maybe part of what makes Pharrell look forever young is his youthful approach to fashion, although we can't recommend you try this look at home.

We'd have a glow, too, if we hung out with Mariah Carey, as Pharrell did in Paris in March 2006. The pair were shooting scenes for a music video to go with their single, "Say Somethin.'"

With a nickname like Skateboard P, we know that Pharrell isn't averse to letting some physical activity put the blush in his cheeks.

Seen here with T.I. in 2008, we bet you can't guess how old either of these music stars are. (Give up? T.I. was 28 while Pharrell was 35.)

If we didn't know better, we'd think Pharrell was stuck in some sort of "Benjamin Button"-like aging process, wherein he was born looking 22 and then never ages at all.

In 2010, Pharrell tried to trick us into thinking he was aging with a mustache and a fake gold tooth, but we can see under the mask, P.

Pharrell insists that the secret to his dermatological success is simply washing his face, but we wonder if having an impressive hat repertoire has something to do with it.

From what we know of maintaining good health (and skin), you have to find time to relax, which Pharrell appears to do here at a press conference in Hong Kong in April 2012.

We'll bet you five bucks Jay Z was asking Pharrell about his skincare when they met up at the Barclays Center in September 2012.

Pharrell celebrated his 40th birthday in April 2013, but we wouldn't believe it if he didn't say so himself.

Then again, maybe Pharrell's passion for what he does helps him look so refreshed. He was clearly thrilled to take the stage with Nile Rodgers, left, and Stevie Wonder at the 2014 Grammys.

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• Fans across the world seem to be in love with the infectious "Happy"


• The song has shot to No. 1 in more than a dozen countries


• Pharrell says he is overwhelmed by the reaction

(CNN) -- There are happy songs -- and then there is "Happy."

The bouncy tune by singer/composer/producer/rapper Pharrell Williams has occupied the No. 1 spot on the charts for more than a month.

It's spurred countless covers -- including one by Academy Award-winning actress Gwyneth Paltrow, reprising her guest star role in the 100th episode of "Glee."

There is even a YouTube version of "Happy" that has gone completely to the dogs.

What is it about this song, which is so infectiously enjoyable that Meryl Streep had to shimmy to it when Williams performed at the Oscars?

Is it the catchy melody? Is it the insistent nature of such lyrics as "Clap along if you feel like happiness is the truth"? Is it that extra bounce you feel when the back up singers airily croon "Because I'm happppppyyyy"? Or is it the joy of watching Williams and several other folks dance, bounce and lip-sync along with the song in the music video?

Yes.

Simply put, the song is all those things, even as it has managed to seemingly capture the rush of happiness in its lyrics and melody.

Not a bad trick for a tune that slowly grew from a single on last summer's "Despicable Me 2" soundtrack to such popularity that Robert Morast, a writer for the Virginian-Pilot, recently entered into a debate of whether it should be considered for the official state song of Virginia.

"Pharrell's hit track is a jolt of mood-lifting music," wrote Morast, who was more partial to the Carter Family's "Can the Circle Be Unbroken." "And while it's fine to be happy, the best art is crafted with a range of emotional perspectives."

Even with its slow build, "Happy" caught ears from the beginning. Upon release it was quickly dubbed "an instant contender for 2013's Song of the Summer" by Rolling Stone. Since then, it's topped the charts in more than a dozen countries besides the United States, including the United Kingdom, France, Germany and Poland.

Violinist Lindsey Stirling, who's worked with John Legend and mixes classically styled music with electronic dub-step beats, asks simply, how "can you not love ('Happy')?"

"I was with a friend, and when ('Happy') came on, her baby started kicking and trying to dance," Stirling said. "We were laughing hysterically and saying 'Even babies love this song.' "

She said she believes the reason "Happy" is so beloved is because of its uplifting message.

"I get so excited when something this positive goes this big," said Stirling, whose album "Shatter Me" will be released at the end of April. "It's spreading good feelings and isn't at all controversial. It's just something that is making people really happy."

Williams has partnered with the United Nations Foundation in celebration of Thursday's International Day of Happiness, encouraging fans to donate to the organization and submit content to his 24Hoursof Happiness.com site.

Visitors were asked to tag their submissions, be they dancing, singing or just "being happy" with the #HappyDay. At noon Thursday, in each time zone around the world, Williams will highlight some of the best.

"Happy" is also one of the lead singles on Williams new album "Girl," which has already shot to No. 1 in almost 80 countries and on streaming music giant Spotify. The singer is overwhelmed by the goodwill.

"This is probably the most I've ever been humbled in my entire life," Williams told the Los Angeles Times about his song and the reaction to it. "Because it's something bigger than me, bigger than anything I've ever done."

No doubt that makes him happy.