Let's break One Direction down to the basics for a minute: They're five British and Irish boys who have achieved worldwide fame through (at least, in part) wearing cool, color-coordinated outfits, having awesome hair and singing ultra-catchy pop songs. With a blink-and-you'll-miss-it rise to superstardom, Harry, Niall Liam, Louis and Zayn have quickly secured a position in the hearts, minds and iTunes libraries of teenagers across the globe.
But what exactly happened along the way that made them into such a mega-phenomenon? We've highlighted 10 crucial moments in 1D's evolution, from their first awkward solo auditions on "The X Factor" UK to playing in front of screaming sold-out crowds on their US tour. Click through the slideshow below for a video history of the band that's got that "One Thing."
How many of these One Direction moments do you remember? Which video is your favorite? Sound off in the comments below or tweet @HuffPostTeen!
August - December 2010
Niall, Zayn, Liam, Harry, and Louis auditioned separately during Season 7 of <em>The X Factor UK</em>.
At the <a href="http://www.digitalspy.co.uk/tv/s103/the-x-factor/news/a331792/nicole-scherzinger-i-did-simon-cowell-a-favour-with-one-direction.html" target="_hplink">suggestion</a> of <em>The X Factor UK</em> guest judge Nicole Scherzinger, the five boys were put together as one group.
February - April 2011
One Direction embarked on a tour following their stint on <em>The X Factor UK</em>. In this video clip, the boys talk about their favorite parts of touring and what they're most looking forward to next.
One Direction releases their first single, "What Makes You Beautiful." It <a href="http://www.metro.co.uk/music/875276-one-directions-debut-single-what-makes-you-beautiful-set-to-top-charts" target="_hplink">debuted at #1</a> on the UK Singles Chart.
In February, One Direction began its first U.S. tour as <a href="http://www.unrealitytv.co.uk/x-factor/x-factors-one-direction-announce-american-tour-dates-and-us-release-date-for-debut-album/" target="_hplink">Big Time Rush's opening act</a>.
The band makes its U.S. television debut on <em>The TODAY Show</em> to an <a href="http://www.billboard.com/features/one-direction-the-wanted-the-billboard-cover-1006560552.story#/features/one-direction-the-wanted-the-billboard-cover-1006560552.story" target="_hplink">estimated 15,000 fans</a>.
The band's debut album, <a href="http://www.ew.com/ew/article/0,,20578458,00.html" target="_hplink">"Up All Night,"</a> was released globally in early 2012. It hit stores in the U.S. on March 13, 2012.
"Up All Night" debuted at No. 1 on the Billboard Top 200 during its first week in the U.S., a feat that not even the Beatles managed to pull off during their heyday.
The band went back to the studio to begin work on their <a href="http://www.examiner.com/article/one-direction-gives-updates-on-second-album-niall-horan-plays-guitar-on-album" target="_hplink">second album</a>, which may be out as soon as Christmas.
As their "Up All Night" tour ends, the boys give an interview in Florida. They dish about whether they'd date a fan, what they miss the most about being a normal teen, and going commando!