MSN is the only search engine to offer some of the more advanced demographic features, though Yahoo and Google offer some targeting tools and are expected to add behavioral and demographic targeting features similar to MSN soon.

"I don't think it's too far-fetched that the other engines will follow suit. This is where pay-per-click marketing is really going to go," said Danielle Leitch, executive vice president, client services, at search marketing firm MoreVisibility, Boca Raton, FL.

Understanding which keywords lead to more conversions with female versus male customers, for example, will help advertisers determine how much to pay for certain keywords, Leitch said yesterday.

Search marketers at least should develop a basic profile of their customers and conduct research on keyword trends so they know which terms are most popular with their customer base.

And through Yahoo Fusion Marketing, marketers can target searchers with certain interests based on their online behavior, said Dana Todd, co-founder and principal of search marketing firm SiteLab International Inc.

Advertisers can target certain customers by terms searched, pages visited, ads clicked on and products purchased. SiteLab tested one advertiser's behavioral-targeted ad units in Yahoo Mail and found that impressions, searches and conversions were higher on those ads.