A website must be Search engine friendly if it is ever to achieve a good position in the major search engines to achieve this is should:

Use intelligible links between pages,

Should never be made in Adobe Flash,

Should never be made up of images - Because of many of the same issues related to using only Flash (mainly there is no content to index).

Should have a nice easy to use navigation system.

There are tons of things a website owner and website developer can do to ensure their site is SEF and designed for optimum search engine compatibility see articles about Flash and SEO for more.