When Liam suggested "Unique Selling Point" during a brainstorming session, Louis had to speak up. "That is the worst!" he reportedly said. "Although, to be fair, you have to be brave even to mention it in the first place."

Harry was the lead singer in the Cheshire-based band White Eskimo before trying out for "The X Factor." The band's drummer, Will Sweeny, actually had to convince Harry to get behind the mic.

The boys' fellow British pal Ed Sheeran wrote the song. "It was a song I was never going to use [so] to have it on a multi-platinum selling album is quite nice," he said.

It means "Be true to who you are," because Zayn "doesn't believe in changing for other people."

Taylor all but confirmed that "I Knew You Were Trouble" was about Harry after her performance of the song at the 2013 BRIT Awards. "It's not hard to access that emotion when the person the song is about is standing by the side of the stage watching," she told 'The Times of London' about Harry.

After the guys got famous, rabid Directioners scoured the Internet for any and everything they could find about 1D. One gem that popped up: Niall's old email address, "da_pimp_is_here_." Ahh, 16 year olds.

The avid soccer player signed to the Doncaster Rovers as a defender in August.

When Liam was younger, he was the third best 1500-meter runner in his age division in England. "Running in the Olympics would have been my dream," he said.

1D became the first U.K. group to debut at No. 1 with their debut album 'Up All Night.' Previously, the Spice Girls had the highest charting U.S. debut in 1996 with their first album 'Spice.'

4. Harry said about his special DNA, "I must have been a twin, but the other one went away and left its nipples behind."