Jakob Nielsen's Alertbox, April 10, 2012 Summary: Good mobile user experience requires a different design than what's needed to satisfy desktop users. Two designs, two sites, and cross-linking to make it all work. Based on usability testing of hundreds of sites, the main guidelines for mobile-optimized websites are clear: Build a separate mobile-optimized site (or mobile site) if you can afford it.

Web usability guru Jakob Nielsen has come under fire for his latest suggestions on building mobile websites. Nielsen's controversial advice can be distilled down to this nugget: "good mobile user experience requires a different design than what's needed to satisfy desktop users. Two designs, two sites, and cross-linking to make it all work."

Earlier this week usability pioneer Jakob Nielsen published guidelines recommending separate sites, cut-down content for mobile and auto-redirects to mobile sites. He says that although expectations for what can be accomplished on mobile are rising, a link to the full site should be enough to satisfy users who haven't found what they need on the mobile version.

For all of Jakob Nielsen's many great contributions to web usability over the years, his advice for mobile is just 180-degrees backward. His latest guidelines perpetuate several stubborn mobile myths that have led too many to create 'lite' mobile experiences that patronise users, undermine business goals, and soak up design and tech resources.

Jakob Nielsen's recent post outlining his recommendations for mobile sites based on large-scale usability testing has come under fire from others in the industry. Here he responds to some of the main criticisms. .net: The strategy of forking content for separate sites has been described as "a content strategy nightmare" - it's too hard to maintain and will result in inferior experience for users.

The experience of using a mobile website should naturally be different from a desktop experience - not just visual presentation, content should be prioritised and structured differently. The risk, though, is that you'll wind up maintaining different versions. News flash: this will be a disaster. Duplicate content. Out-of-sync updates. Wasted effort.