Moz is an independent company that comes out with metrics for a large number of websites. The various metrics are given below
MozRank: MozRank is akin to Page Rank. It's a link popularity score - which goes from 1 to 10. Domains/Pages earn MozRank based on the quality and number of other pages that link to them. An average MozRank is about 3.
MozRank (www): This is the MozRank for the www subdomain
Combined MozRank: This is the MozRank of all the pages on the root domain combined into a single value
Combined MozRank (www): This is the MozRank of all the pages on the www subdomain combined into a single value
MozTrust: MozTrust is Moz's global link trust score, that measures the value of links recieved from trustworthy websites. It goes from 1 to 10.
MozTrust (www): This is the MozTrust for the www subdomain
Domain Authority: DA shows how well a domain will perform in search engine rankings. It can be used to compare one domain to another and is therefore a better metric than MozRank when valuing domains. The metric is scored from 0 to 100. Because DA is difficult to directly influence it is hard (not impossible) for scammers to fake a high DA.
Page Authority: PA shows how well a given webpage will perform in search engine rankings. Since PA predicts the probability for a single page, it is not as useful as DA when it comes to expired domains. Like DA this metric is scored from 0 to 100.
Total Domains: This is the total number of domains with back links to the root domain
Total Domains (www): This is the total number of domains with back links to the www subdomain
Total Back Links: This is the total number of back links that Moz has found.
Total Back Links (E): This is the total number of back links which pass equity to the root domain.
Total Back Links to Sub Domain(E): This is the total number of back links which pass equity to the www subdomain.