SEO Best Practices
3.1.1 Weighted Relevance
As in the index card system, when one perused the files, book titles carried more weight than just a chapter. Keywords and summaries carried less weight than book titles. Main chapter listings carried more weight than sub-chapter listings. And so on.
The same goes for a web page. Different page structure elements will weight differently for relevance. Proper optimization can be achieved by making sure the targeted keyword phrase appears in all the core elements.
Note: in the past, webmasters began stuffing keywords in the meta keywords section. Many Search Engines ignore the meta keywords. However, this does not mean that it isn't important and can be ignored.
Note: The meta description is an important element in that it is usually the summary listing first shown in the SERPs when a new page is freshly indexed. Making good use of this by utilizing descriptive text dialog structured to encourage buying can make a difference in a page's click rate.