Through profiling, now ad companies know — or, at least, aim to know — exactly who is reading a certain site or watching a certain video.br Ad companies don’t just know the user, but they also know the user’s context — for instance,br whether you’re at work or at home, or whether you’re in the mood for shopping or not.br One consequence of this model is that it pays for a lot of contentbr that wouldn’t have been funded under the old model — now a teenager can attract a few million followers on YouTube, sign up for the company’s revenue-sharing program and make money from all of the programmatic sponsors.br “It wasn’t possible for us to be certain that we were reachingbr that audience, so we used the content of certain programming to define that audience,” said Brian Lesser, the chief executive of GroupM, a division of the advertising giant WPP.br In other words, instead of targeting men, they’d run ads on shows they thought men liked to watchbr — a good enough solution, except for all the women and non-shavers who were also watching.br And given that advertising pays for nearly the entirety of what we see and do online, the upside of all the hand-wringing isbr that we are now examining how all of that money gets spent — a process that should lead to better ads, and better media, too.br Luckily the people were easy to find: They were all watching or reading one of a handful of mediabr offerings — three TV networks, some big glossy magazines and one or two newspapers in every town.