Usability Standard 9:
Help the User Recover from Errors

Error messages should be expressed in plain language (no codes), precisely indicate the problem, and constructively suggest a solution.19

From the classic "404 File Not Found" to the mysterious "ODBC error," most error messages on the Web are less than helpful. Whether addressing a server problem or a user mistake, error messages should be understandable and allow the user to either correct the problem or move on.

Be sure to explain unsatisfactory search results too. If a user's search returns no results, offer advice on broadening the search parameters and provide another search opportunity right there on the result page. If the search returns too many results, tell the user how to restrict the search, or allow the user to search within the results for a closer match.

If possible, anticipate a user's needs by taking the user directly to a particular page if a certain search parameter is used. Search for "book" on Amazon.com and you get more than 30,000 results. Why not just go directly to the top-level books page? By contrast, if you typed "furniture" in a search box on lifestyle retailer Living.com, the site skipped the search results entirely and delivered the user directly to the furniture section.

(However, the now-defunct Living.com overlooked a much larger usability issue: people want to sit on furniture before they buy it.)