How, Exactly, Do You Define 'Youth'?

I'm heading to Tokyo in a few weeks for a pan-Asian Digital Youth conference and thinking a lot about the "youth" part of that topic. When I hear Mimi Ito's great ethnographic work on teens or read danah boyd's research and interviews with teenagers, I think about close social networks where technology simply enhances those networks. Boyd notes that, for teens, social network sites are not primarily about "networkING.  They are about socializing in a networked peer public with one's social network" (MacArthur Forum, 23 April 2008).   She notes that their "online world is a reproduction of their offline peer networks.  Their social interactions move fluidly between online and offline environments." But what about for youth who are no longer teenagers?   The biggest difference from teen years for most (of course this is a socio-economic as well as a cultural category) young people in the over 20/under 30 age is having to support oneself.   The economics of self-sufficiency (or even the expectation of self-sufficiency) configures "youth" very differently for twenty-somethings.   I am thinking about this a lot as I digest some recent correspondence I've had with Liz Dorland, conducted on Facebook and also about it and what it means to be a "Facebook Friend."   She notes that her friends from her online Second Life and other virtual communities often use social networking sites not only for "networkING" but for credentialing information and spreading it among those within the network.   That might mean 150 or 500 or 1000 "friends."  You don't have to treat them all (or even a small fraction of them) in a personal way but, rather, the extended network is a source of good information about digital youth topics and helps filter the insane amount of information on the network through a social community that is relatively small and targeted.  This conversation with Liz makes me think about a term familiar to academics: "Peers."   Do those who live in virutal communities for much of their lives then use social utility sites such as Facebook as a peer review system for information, events, and services in the vast world of the Internet?   Interesting.  Do we need to refine "digital youth" and think more seriously about the socio-economics of that term?   Who would have guessed it? That's pretty much how life works without technology! As my former boss, the late John Strohbehn, used to joke, if we didn't expect there to be a major change in kids' affective and social lives between the ages of 18 and 22, we wouldn't be charging tuition!  It's not just about learning disciplines but also learning discipline---the kind you need to enter a workforce.   All this makes me understand that, for a conference on "digital youth," we need to be paying as much attention to what "youth" means in different cultures and in different economies (such as post-bubble Japan or the current recessionary US) as to digitality.  "Digital Youth," in other words, is a term in which each word defines and inflects the other. Any thoughts on this?  [Photo credits, courtesy of Flickr, with thanks to Brett Walters and  New Media Consortium]