Can you please provide an explanation of what each grade means so that I know how to improve the grade?

[WebsiteGrowth]

I am actively using SEOMoz to improve our overall customer experience and increase SEO traffic.  I would like to better understand the grading "report card" report to deep dive into the words that get a poor score.  Example I understand that "F" is bad, but what scoring factors are used to determine an "F"?

[dawnieando]

The help pages on SEO Moz will give you a lot of guidance as Keri says.  I'd seriously recommend making sure that where you can you ensure that your page gets an A or B by going systematically through the recommendations that the on page research section of SEO provides.  I've seen considerable gains from just making sure that a page ticks all the boxes listed to take it from an F to an A.

On page Old stuff still has a part of play

[KeriMorgret]

Here's some information about our grading that should get you started http://www.seomoz.org/help/on-page-reports. Let me know if that helps!