The Internet search engine is an indispensable tool of modern life and an advertising gold mine for Google, the favorite first stop on the Web.

But searching accounts for only about 5 percent of the time people spend online; the other 95 percent is spent on the wider Web, where a different advertising landscape looms. Instead of the short text ads that appear on a Google results page after a search, visitors often find display ads that are the Internet?s equivalents of glossy magazine ads or television commercials. These are typically the province of brand advertisers like Cadillac and Coke.

Until recently, however, it was impossible to tell whether these ads were in fact reaching their target audiences because no one had applied the computing tools and powerful mathematical analytics that were needed to link online display ads to specific markets. But that is changing, and a number of small companies are standing at the forefront of this transformation.

Get the full story at The New York Times