For example, Inktomi, the largest paid-inclusion provider, operates Index Connect, which lets small and medium-size sites pay a flat annual fee to have their Web addresses regularly indexed. Larger sites such as Amazon.com and eBay -- which typically want assurance that more than 1,000 addresses are indexed -- pay on a sliding scale, depending on the category. These sites can pay anywhere from 15 cents to $1 each time a Web surfer clicks on a listing -- which is akin to the paid-placement model.
In contrast, Google delivers unbiased search results from a vast index of Web sites; the company does not accept fees for cataloguing sites.
Paid inclusion has sparked ongoing concerns that the public might be misled about the independence of search listings, however. While Yahoo argues that paid inclusion produces unbiased, relevant results, search engine experts say that the practice is widely known to give the listings of marketers higher rankings in the index.
"Search engines like to say it doesn't affect the rankings. But there have been cases where rankings on AltaVista and Inktomi were boosted [for marketers that pay]," said Danny Sullivan, an editor of Search Engine Watch, an online industry newsletter.
"It's much more noticeable then it was in the past," he added, even though out of the 1.5 billion Web pages being indexed, only about three million pay to be crawled more often. "The way that it's mixed in with ordinary content can be favourable to [marketers]," he said.
Sullivan added that there's little to no disclosure for these kinds of commercial results.
"Consumers have no idea that this is happening, and at the moment, that's in line with what's the FTC has said -- that paid inclusion doesn't need to be segregated, if there's no boosting happening," he said. "I'd suspect if they were to look at it, and saw that boosting was there, they'd want it to be separated."
