Keyword Prominence is considered by most SEO experts an important factor in website optimization.
Keyword Prominence is the position of keywords in your HTML. The closer to the top of the page your keywords are, the higher prominence those keywords have. Let’s say that a keyword appears near the top of your page in the first sentence. If it were the first word on the page it would have a keyword prominence of 100%. If a keyword appears in the middle of the page it might have a keyword prominence of %50. If the keyword appears at the very end of the document it would have a keyword prominence of 0%. Keywords with higher prominence are considered by the Search Engines as more important.
What that means is that you should put the keyword phrases you are targeting for a given page as close to the top of the document as you can.
Your keywords should appear throughout the rest of the document as well. Some people believe that you can raise the prominence by using the DIV tag instead of Tables, because by using DIV tags you can place your keyword text at the very top of your HTML code. A DIV tag is a tag that allows you to apply styles to the text that is placed inside the DIV tag. I have not personally noticed DIV tags making a big difference, however using DIV tags does have the advantage of making pages load faster which can help your conversion rates.