Time online is rapidly displacing TV time in most American households. Multi-tasking is being enabled in new and interesting ways by the convergence of telecommunications, the Web, and social media. People can simultaneously publish and consume content, communicate, and make a living while riding the train to their day jobs, sitting in a coffee shop, or on a lunch break. This is what is exciting about the times in which we live. However, it is also true that there are still only 24 hours in every day and that nearly all of us have responsibilities that preclude us from spending all of our time consuming content and information online. I'm not exactly sure where the asymptote representing the maximum amount of time any individual will spend online in search of or consuming information but let's assume it's around 8 hours for the sake of argument. Some of this time will be spent by the individual in lean forward fashion - searching, clicking, scrolling, etc. The rest of this time will be spent in lean back fashion - watching YouTube videos, browsing MySpace, etc. It seems to me that the former context (lean forward) is the sweet spot for premium performance-based advertising. When people are in lean forward mode, they're much more likely to be searching for something to consume. They're effectively shopping for information which presents real commercial opportunities to advertisers. Maximum eCPM is the name of the game here. The latter context (lean back) is a bit trickier from an advertiser's perspective. In that context, a person is seeking a passive experience - they want to be entertained. As a result, they're less likely to be commercially inclined but more open to messages and content that could shape preferences. The value to advertisers here is, in my mind, about branding and large numbers. The effectiveness of ads in this context should be measured more in terms of the impression levels and frequencies. As video becomes more and more a part of the fabric of the Web, my guess is that lean back will displace a bit more of the time we spend today in lean forward mode. Right or wrong, the majority of us will choose a lean back experience over lean forward when given the opportunity. As more lean back content becomes available, many of us will spend more time watching and less time clicking. A few take-aways in all of this are that content producers still hold the keys to value creation online in either context. In the lean forward context, the leading search providers (in the broadest sense of the term) will continue to see consumer and advertiser demand accelerate. In the lean back context, the large aggregators and social media hubs like YouTube, MySpace, FaceBook, as well as big media (Disney, Time Warner, News Corp) will see traffic numbers and time-per-session continue to grow to the benefit of advertisers seeking opportunities to shape preferences and build brands (ie P&G, Toyota, Fidelity, etc).