Nobody seems to remember the old ecosystem, much less why it went extinct. That's problematic if we want to avoid extinction ourselves. But there are quite a few of us old-timers left around who remember when search advertising was a display product. Advertisers bought keyword-triggered banners on a CPM basis from the likes of Lycos, Infoseek, and HotBot. More often than not, all those big "portal deals" that made headlines in the mid-1990s contained a rather sizeable component of search inventory, and you could buy whatever keywords you wanted -- even if they were completely irrelevant to your business and what you were selling.
