Happy - From "Despicable Me 2"

Most hit songs around this time were written by teams of writers, but this one was entirely composed by Pharrell Williams, who was formerly the N.E.R.D lead vocalist and Neptunes producer. He wrote and recorded the song for the soundtrack of the 3D computer-animated action comedy film Despicable Me 2. Williams also penned tunes for the first Despicable Me flick, including its lead single, "Despicable Me."

Finding a way to follow a trend and be unique at the same time seems like an impossible task, but that is exactly what Williams was facing with "Happy." It could have easily drowned in the stream of other songs - like "Treasure," "Blurred Lines" and "Get Lucky" - that blended R&B, funk and soul if not for some clever techniques to help it ride the wave to the top of the charts. For one, it had to be an earworm, and to do that, repetition is key. Aside from repeating the uplifting title 56 times, over 62% of the song is dedicated to its memorable chorus (about 20% more chorus time than most hits of the era). To make room for that monstrous chorus, there is no pre-chorus, solo, instrumental break or outro.

The song's visual is the world's first ever 24-hour Music video. The clip was directed by the creative duo We Are From L.A. and was filmed entirely on Steady Cam, requiring the crew to walk nearly eight miles per day over the course of 11 days. The visual plays on an all-day loop and follows more than 400 different characters enjoying daily bliss. As well as everyday people dancing through the streets of Los Angeles, we see a host of familiar faces having fun, including Despicable Me 2 stars Steve Carell and Miranda Cosgrove and Williams himself, who appears 24 times. Also showcasing their versions of happy are Tyler, The Creator and Earl Sweatshirt from Odd Future. Kelly Osbourne, Sérgio Mendes, Ana Ortiz, Issa Rae, Bevy Smith, Magic Johnson, Jimmy Kimmel Steve Martin, Janelle Monáe and Jamie Foxx. And naturally the Minions pop up in the day long promo. Those with a whole day to kill could check out the full version of the video on the now-defunct 24hoursofhappy.com. A more time-friendly version clocks in at 4 minutes and 7 seconds.