"These are not just ad companies, but marketing services companies, too," she said.

She was a model his ad company had hired for commercials.

The battle now among ad companies is to deliver an even narrower demographic slice to clients.

This information helps ad companies display advertisements that are more narrowly targeted to the interests of individual users.

His first big hit was Zip2, a Web-based ad company that he sold in 1999 for $307 million.

Building the world's largest ad company was that simple.

Now, they think the ad companies should be responsible, too, for not being careful about whom they do business with.

Virtually everyone is known, on sight, by ad companies who use computers to target not just groups of consumers but individuals.

Traditional ad companies, with their human-touch marketing skills, will always have an important edge over Google, he said.

Some industry watchers challenge the assumption that the ad companies are quick to feel a slowdown in the economy.