Online advertising in the mid-1990s copied print and TV: buy a block of impressions, pay per thousand views, and hope. Gross later described the model bluntly as buying ads, crossing your fingers and hoping it worked out, because an advertiser paying for exposure had no built-in signal for whether that exposure did anything. Search engines had the added problem of needing revenue without corrupting results — ranking pages by who paid the most for placement, with no other pricing signal, risked flooding results with irrelevant paid listings dressed up as answers.
Charging advertisers more for a bigger banner or a longer campaign wouldn't fix the underlying disconnect between payment and outcome — the industry needed to tie the money changing hands to something the advertiser actually wanted, which was a visitor arriving at their site, not merely an ad being displayed to someone who might ignore it.
Charged only when a user clicked, with advertisers bidding in an open auction for keyword placement, so the market priced attention and payment matched engagement.
Charging per click meant payment only happened when the ad demonstrably worked, removing the risk of paying for ignored impressions.
An open auction let the market, not a rate card, decide what a keyword's attention was worth, aligning price with demand.
Separating paid listings from organic results kept search quality intact, avoiding the corruption of ranking by payment alone.
Advertisers self-selected by what a click was worth to them, making the model self-funding without manual pricing.
When buyers want an outcome, charge for the outcome, not the exposure, and let an auction set the price.
Google adopted the same click-priced auction for AdWords in 2002 and paid Gross's company roughly $360 million to settle patent claims. Pay-per-click auction pricing became the default mechanism for virtually all search and much of digital advertising worldwide, and Gross's own missed patent filing on it became a cautionary story he calls a trillion-dollar lesson.
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