There are several types of errors of accessibility and usability common among web-designers and aspirant web designers, whyyou should eliminate them from your site should be a question with an enclosed answer: if there are problems it’s obvious that they have to get resolved and eliminated. The best thing would be to eliminate the problems upstream, making accessibility and usability you’re form mentis: you should correct your approach towards the web before you commit a mistakes. However, in all cases, whether the mess is done or the confusion is only in your mind, we’re going to see how to eliminate the most common problems that make your site less accessible and usable.