PageRank
PageRank is Google's original algorithm for scoring pages by the quantity and quality of the links pointing at them. The public toolbar score was retired in 2016, but link-derived authority remains a core part of how Google ranks pages today.
Why it matters for your rankings
PageRank is the idea that made Google work: a link is a vote, and votes from important pages count more than votes from unimportant ones. That recursive definition is still the intuition behind link value.
Understanding it changes how you think about internal linking. PageRank flows through links, so a page receiving links from your strongest pages inherits some of that strength. It also dissipates: every hop loses a little, and pages with hundreds of outbound links pass very little through each. This is why a well-linked site structure outperforms a flat pile of pages, and why burying a commercial page six clicks deep starves it of the authority your homepage is receiving.
How to check it on your site
Map where your authority sits
Ahrefs Best by Links shows which of your pages hold the most external link value. Those are your distribution points.
Check they link onward
Confirm your strongest pages link to the commercial pages you want to rank, with descriptive anchor text.
Shorten the path to money pages
Reduce the number of clicks between the homepage and revenue pages so less value is lost in transit.
Remove needless outbound clutter
Trimming low-value links on key pages concentrates what passes through the remaining ones.