When used correctly, graphics add to the attractiveness of a web site and contribute positively to a visitor's first impression of the site. However, the reverse is also true. If a web site is unattractive, a visitor will be negatively affected and may click away from the site, never to return.
Use common sense when including any graphics on your web pages. More is NOT better! Don't plaster your site with graphics, clip art, and animated gifs. An excessive number of graphics makes for slow page loading times, clutters the web page, annoys visitors, and makes it difficult for a potential customer to read a sales message.