At eighteen, we wear what everyone else wears. Most of us are frightened of individuality at that age, not least when we're far away from home and trying to fit in (students etc).
Therefore, most of teen culture since the 1950's has involved some sort of uniform that, in one contradictory swoop, enables them to gently rub against the generation that came before, flick the bird to the grown-ups and utterly conform with each other. Few have had the self confidence to be different and ignore what everybody thinks and wears.
A few years ago, teenage girls mostly worse low rise jeans to expose the muffin topped belly.
Then it was skinny jeans forced into whatever size legs they had with smock tops.
From that basis of conformity, as we grow as people and construct our identity, begin to branch out.
Well, sort of anyway. These uniforms always reflect shifts in society, that's why I find it daft for sniffy intellectual types to dismiss fashion, it's a beacon of the times it lives in. In the 1950's it was the twinset, in the progressive 60's it was the miniskirt (but for much less of it than most assume).
Clothes in the 60's represented the emancipation of female bodies, largely tearing apart the soft femininity and elegance of Diors 'New Look'.
The liberation of shoes without massive heals literally as well as metaphorically took women to places they'd found hard to explore before.
In other words, clothes wear us as much as we wear them, which is why, it's so interesting to look at the way young people really dress now.
No longer is it one uniform. For a bit it was the uniform of the tribe, lots of different accepted ways of dressing to fit in, but contemporary youth fashion, and even more the grown up version, is now porous, just as culture has become so.
If there is a uniform, it is incredibly subtle as they constantly mash it up and swap identity. The codes are so subtle that only the most attentive observers can understand it. It is still uniform, but, like the secret handshake, only those in the know get it.
Which means that if you're doing anything with 'yoof' as a marketing type, you either have to absolutely on the money if you try and mirror their lives back to them, or instead, both harder and easier, have a big, motivating, provocative vision for them to partipate in, that zones in on a searing cultural issue or need.