The Arts and Sciences of site design. Unlike making style judgements on printed pages, web designers need to work with differing sizes and types of monitors in mind.
Graphics design is also quite different on the web.
Not all users are equipped with a digital artist's monitor and video card - they may not even have their graphics driver set above 16 colors. Another factor in designing web graphics is that color depth equals file size. However, with the many commercial interests now involved, many different programs and platforms have evolved to muddy the waters. We also test each site to make sure users are able to see it as well as their equipment allows. The use of proper HTML tagging is critical to page design.