"And at the same time, a lot of new technologies emerged that allowed us to do better things with delivering ads."

The goal was to deliver relevant ads based on browsing history.

AudienceMatch helps publishers deliver ads to a niche audience without collecting personal information.

And they are hoping to help deliver ads to online video games, cellphones and Internet television services.

But the industry is divided on the best approach for delivering such ads.

The software usually delivers pop-up ads, but sometimes performs other actions without the owner understanding what is going on or how to stop it.

"We'll know for certain which agencies consistently deliver ads that perform well," he said, "and which ones cannot."

Cookies also can be used to customize your browsing experience, or to deliver ads targeted to you.

They may be used to deliver ads tailored to your interests.

The Web sites, accordingly, charge a premium for delivering ads aimed at certain users.