On DigitalPoint and some other big websites, they use it to rank a website's power much as Google PageRank once did. Note, to my knowledge, page authority tells about the power of specific pages, while domain authority refers to a whole website's ranking ability.
Anyhow, PA when seen on the web probably refers to an average of PA, cause each page has something different.
Anyhow, PA when seen on the web probably refers to an average of PA, cause each page has something different.