Search engine optimization (SEO) is the process of improving the visibility of a website in search engines via “natural” or unpaid (“organic”) search results. It’s one of the areas that you need to get right when developing a website, and an area to tweak when you try and improve the rankings of your website, over time.
I came across this infographic, which set out all the factors as a periodic table.
It shows the things you have to get right – all common sense really, and unacceptable behaviour which you will get punished for.
Wish I had seen this back in 2007, would have made things alot clearer.