And to be a little less geeky...
(In general, there are always exceptions)
If you do your website in Flash, or use a lot of Java Script, etc. it makes it harder for the search engines to "see" the content.
If your site using HTML or XTML text, with tags on the images, it makes it easy for search engines to see it.
Do your text as graphics (gifs and jpgs) makes it impossible to search.
Other sites linking to yours - people going to your site - raises its search engine results.
What search engines are looking for is relevancy, not keywords. So writing - and posting - is good. That's why blogs do better than static sites in general.
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