Web design
According to Wikipedia, web design is defined as: "the skill of creating presentations of content (usually hypertext or hypermedia) that is delivered to an end-user through the World Wide Web, by way of a Web browser or other Web-enabled software like Internet television clients, microblogging clients and RSS readers".
Firsts Impressions
First impressions last, therefore it's extremely important to take the visual appearance of your site seriously. A good website design, should convey your corporate image, whilst communicating on subsconsious levels with the visitor. Conveying the site's main purpose, as well as leading the visitor to the next step you want him to take, is important.
Clearly Defined Goals
Taking Google.com's very plain and straight forward design as an example; design shouldn't always feature so high up in the priorities list for a site. The main consideration should be the site's main objective, and everything should be done so that the site should reach its goals.
Internet Speed
Large graphics and animations increase the size of your website, and therefore increases bandwidth used by your site, and also increases loading time for the visitor. While broadband penetration is increasing world wide, various optimizations should be implimented to ensure that the visitor has an enjoyable experience on your site. A balance should therefore be kept between the various aspects that influence the visitor experience.
Please see the following: