For many people, it's hard to imagine a wardrobe without a single T-shirt in it -- but they didn't exist at all just a century ago.
On Thursday, the T-shirt turned 100 years old -- and it's a purely American invention.
While T-shirts can be a simple something to wear, they can also become mementos of memorable occasions and accomplishments.
Some people, like the girls waiting the One Direction concert, use them as a canvas in the hopes that they will get noticed.
Almost everyone has a T-shirt they probably shouldn't keep anymore, but the clothing staple shows no signs of disappearing any time soon.
The T-shirt got its start in the Navy 100 years ago and it remained in the realm of underwear until the 1950s, thanks to Marlon Brando.
In the 1960s, people started to tie-dye them. In the 70s, decals became the embellishment of choice. In the 80s, Don Johnson began wearing a T-shirt with his suits.
Now, entrepreneurs like Brian Felson base their businesses on cool T-shirts. He started the 612 clothing line and is now branching into the LGGK line, which will partly benefit people with hearing loss.
He's not the only one cashing in on the century-old garb. Clever T-shirt businesses abound online.