The New York Times Agency Photos
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At AppNexus, from left, Michael Rubenstein, president; Brian O'Kelley, chief executive; and Mike Nolet, technology chief in New York in March 2010. AppNexus is one of the companies helping marketers automate their analysis and bidding. Companies like Google, Yahoo and Microsoft are now capable of letting advertisers buy tailored ads in the milliseconds between the time someone enters a site's Web address and the moment the page appears. The technology, called real-time bidding, allows advertisers to examine site visitors one by one and bid to serve them ads almost instantly. (Joshua Bright/The New York Times)