First, let's go back to the 2000s. Who could forget Abercrombie & Fitch's shirtless models? Note the woman in a semi-compromised position wearing low-rise jeans and a white camisole — a faceless trend.
It was in 2006 that former CEO Mike Jeffries told Salon that Abercrombie was supposed to be for the "cool kids." This, apparently, was a cool kid, wearing the necessary in-style fringed-denim skirt.
Aeropostale was a mall staple, telling the world that couples who dressed alike (in monochrome outfits completed with denim) stayed together.
Teens loved logos.
Don't forget: The early to mid-2000s were defined by some particular looks. Mandy Moore — here in Fred Segal in California in 2005 — appears to be in the midst of many of them.
Here's Taylor Swift in 2006, wearing a very 2006 dress. It's pretty on brand for Taylor Swift 10 years ago, too.
Here's another very 2006 look, courtesy of Hilary Duff ...
... and don't forget something that's hopefully a bygone memory now: cargo pants (courtesy of Ciara).
American Eagle displayed optimism 10 years ago ...
... and graphic tees.
Wet Seal was still popular (as were chunky accessory belts and white lace skirts — a must).
Now teens love Brandy Melville and its simple aesthetic.
Its infamous "one-size-fits-most" sizing doesn't seem to bode well with the body-positivity movement, but the company's marketing schemes appear to resonate with young people.
And this is what Abercrombie & Fitch looks like today — certainly more conservative.
As a reminder: This was 2006. Here's Karlie Kloss posing for Abercrombie 10 years ago. Notice the logo — it was like a status symbol back then.
Although Jennifer Lawrence showcased the girl-next-door look for Abercrombie & Fitch in 2006, showing an emerging trend of simplicity.
The real teen winner today? Nike, which, according to Piper Jaffray, has usurped former teen staples like Abercrombie & Fitch in recent years.
Aeropostale has been trying to appeal to today's teens with more fashion-forward options, but the company filed for bankruptcy in May.
As athleisure gains popularity, tween girls have a new option: Lululemon's younger counterpart, Ivivva.
Teens love Forever 21. It ranked No. 3 among upper-income teens, and No. 1 for upper-income females, according to a spring Piper Jaffray survey.
One reason teens love fast fashion? They clothes are cheap, and teens can thereby share multiple outfits on Instagram.
American Eagle was the number two brand when Piper Jaffray surveyed upper-income teens in the spring, bypassing teen stalwart Forever 21. Its aesthetic is slightly different from 10 years ago, though it still appears to maintain its optimism.
American Eagle's popular and rapidly growing lingerie brand, Aerie, was born in 2006. Now it's become famous for its Photoshop-free #AerieREAL campaign.
Teens love the irreverent, slightly offensive Shop Jeen.
Even though teens' looks have changed, they certainly love nostalgia.