Now it seems you can't move in bookshops for the sheer number of books targeted at these proto-grown-ups. I myself have recently tried out for a series aimed and 12-20 year-old males. I've never known of such a categorisation before. From my personal experience I was a very different person at 20 than I was at 12 and am not sure my younger self would have been ready for what my twenty year-old self was reading by then.
YA fiction is being marketed on a vast scale and it seems that everyone* is trying to get in on the act. But is it right to label, or brand, stories in this way? You can guarantee that what's right for one teenager won't suit every youth on the street.
Young Adult Literature (to give it its grander title) has become a genre which covers various text types including novels, graphic novels, short stories, and poetry. Much of what's published consists of young adult fiction which in itself contains several different types of text, but the genre also contains other various types of non-fiction such as biographies, autobiographies, journal entries/diaries, and letters. So basically it's any type of book. Big deal. So what makes it specifically fiction for young adults.
Well, for starters, problem novels tend to be the most popular among young readers; in other words novels that “addresses personal and social issues across socioeconomic boundaries and within both traditional and nontraditional family structures.” Memoirs are also popular.
This most wide-ranging of genres has itself been challenged due its seemingly mature content by critics of Young Adult Literature, but "other converted critics have embraced Young Adult so dearly that they have scoured the canon for any classics they could adopt into the YA family." So, in other words, kids are reading books for adults. Go figure.
I know that my Black Library novels are read by teenagers but I didn't set out to write a book only for them. Heck, my Fighting Fantasy books are written for children, but plenty of adults read those too. But I'll keep plugging away at my attempts to write for the Young Adult market, but at the end of the day what I'm most interested in is telling interesting stories, no matter who they're aimed at.
* I'll happily admit that I'm one of them.