DR. JAKOB NIELSEN is principal of Nielsen Norman Group. He was previously a Sun Microsystems Distinguished Engineer. Nielsen's Alertbox column about web usability has been published on the Internet since 1995 (www.useit.com). Nielsen has been called "the world's leading expert on Web usability" (U.S. News & World Report). MARI E TAHIR is Director of Strategy at Nielsen Norman Group, where she has focused on B2B and B2C user experience redesign. She previously managed the Human Factors group at Intuit, Inc., and at Lotus Development Corp., she pioneered field research and user profiling methodology, and was responsible for the usability of the SmartSuite product line.