Cleanness is essential for a good web design. People often mistake cleanness for minimalism. While both styles have common traits, do not be confused. They are not the same. Minimal design is more about using the bare essentials - less is more. Clean design focuses on the careful and precise positioning of the important elements throughout the site - a place for everything and everything in its place. The website can be considered quite busy with lots of elements to consider, but as long as the design is kept clean, the website will work. Clean website design conveys elegance.
External Links: 10 Principles of Good Design | Dieter Rams' Principles of Good Design Video | Clean Up Your Mess: a Guide to Visual Design for Everyone