Released by the Black Eyed Peas in 2009 as the second single from The E.N.D., I Gotta Feeling became one of the defining party songs of its era, topping charts around the world and soundtracking clubs, weddings and New Year celebrations. Its simple, optimistic chorus made it easy to sing along to, and that familiarity helped it survive long after its chart run. On social media it is now reused as shorthand for a good night, a celebration or a moment that is about to get better.