PageRank

Google’s original algorithm for scoring a page’s importance by the links pointing at it.

The public toolbar score is gone, but the principle still shapes how authority moves through links, internal ones included.

Think of it as a budget a page passes on: linking to a hundred pages gives each far less than linking to five.

It explains why site architecture matters as much as external links.

It is the reason a well-linked internal hub can outrank a better-written orphan page.