Brian: Primary keywords are the ones(mostly one or two) that are given the most importance while optimizing a web page.They appear on the most vital areas like the header – footer – inbound anchor text – H1 tags – Meta tags etc. Primary keywords should be repeated with a certain amount of keyword density through out the page. Primary keywords are the ones that are not used by other sites and is yet to break into a niche.
The secondary keywords are the ones that are less important and supports the primary keywords for its marketing.
If you have too many keywords to target for a website you can divide into primary and secondary keywords. Primary keywords will contain a list of important keywords which best describe your website or business and secondary keywords will contain less important or long tail keywords.
Primary keywords are those that best describe your website or business. Secondary keywords are those that you target for some of your internal pages of the website.