Happy Anniversary To One Direction:

July 23, officially marks the four year anniversary of One Direction forming their band. Fans can't believe how much the guys have grown up in the years since their days on X Factor, and their maturity even reflects in their fashions. In the past four years, Harry Styles and Louis Tomlinson's hairstyles have grown into long manes, Liam Payne has gone from wearing polo shirts to rocking dapper suit jackets, Niall Horan had his braces put on and removed, and Zayn Malik got more tattoos than we can count!

Niall Horan was the first to chime in on their anniversary, tweeting about how he couldn't believe the band only got together four years ago. He finished off with a shocking photo from their X Factordays, saying that his 1D bandmates are "family" to him now

But it wasn't just Niall who expressed his love. Harry Styles and Liam Payne also posted adorable statuses in honor of One Direction's fourth anniversary. Harry gushed about how "lucky" he feels to be a part of the band, and seriously thanked their fans.

Meanwhile, we already know how much Liam loves his fellow 1D members, but we were still touched to hear that he appreciates the band and their Directioners. He echoed Niall and Harry, tweeting that he couldn't believe they had already been together for four years.

As if that wasn't heartwarming enough, Louis Tomlinson recently told Top of the Pops that the band has a little 1D family. "I think 'family' is probably the best way of describing us," he said. "It's different to friendship.”