The design of 404 error pages is often overlooked and underestimated. However, designed carefully, these pages can make a random visitor stay on your website, take a look around and eventually find the information he or she was looking for in the first place. Effective 404 error pages communicate why a particular page couldn't be displayed and what users can do next. A search box and list of useful resources (possibly related to the missing page) could be helpful in this case. We've already...