Though Google leads among search engines and has increased its share of online searches to 41 percent from 31 percent two years ago, searchers continue to use multiple engines and marketers need to consider their ever-shifting loyalty, according to Forrester Research's report "Search Loyalty Is Hard to Find," writes InternetRetailer. Though 40 percent of online users say they are loyal to one of the four large search engines (Google, MSN, Yahoo and AOL Search), 49 percent say they use multiple engines.

Users rated Google most effective of the four engines at most information-related search tasks, whereas Yahoo and MSN were rated more effective in finding music or video content. AOL was rated least effective of the four engines in 11 search tasks about which users were asked.

An implication of consumers' use of different engines is that marketers who depend on search should not optimize only for a single engine to achieve the results they seek. Marketers should use analytics tools to understand how consumers use multiple search engines, according to Forrester.