A Plain Jane web site has much information but is probably unattractive to the first-time user. This can be likened to a genius lady who looks extremely boring. Of course, those suitors who know her capabilities would not mind her looks at all, but it would be extremely hard for her to get a first-time boyfriend.
The same thing applies on a web site. Graphics might be essential to explain your ideas, or it might serve some decorative purpose. Whichever way, even if a user does not pay particular attention to it, the graphic leaves an impression that the web page is more complete and pleasing to the eye
However, putting graphical elements on a web page, especially large ones like photographs, entails a certain sacrifice: speed. This section deals with this problem by introducing several fundamental technics to reduce size but preserve the maximum image quality.