Pretty much any genre but typically about things that interest people of that age groups. The protagonist will usually be on the upper end of the age it is marketed to since that age group is usually held in the highest regard by their peers. They tend to lean towards fantasy but not always. Regardless of the genre the stories often revolve around the things that the target audience's life revolve around, school, siblings, deep earth shattering and time stopping love, being cool and accepted by your peers ect. Not much about things like careers and raising families. The moral issues tend to simplistic with a very black and white answer. The often have very clear social messages even if they are not always messages their parents would approve of. They also have to be clean enough to get past school censures and sell at Walmart.

My oldest kids have about grown out of that group so I guess that rules me out. When I was in that age group they didn’t call it YA but I did read some books that would qualify. It does get to be a little fuzzy and at heart it really is just a marketing tool.