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PA - Page Authority DA - Domain Authority, basically the average of all the DAs

DA stands for Domain Authority. Moz uses the DA algorithm to make a single score for the whole site. The Algorithm takes into account the links pointing to your site, total number of referring domains, total number of backlinks etc. It's co related to how powerful your site is and how would you rank/get traffic from Google.

Darin got there first! Domain Authority. It is the current metric to judge the effect a site has within the algorithm to rank for its niche. I don't want to copy Darin's post, I'd recommend the links he's given you. Happy reading