PageRank is THE original search signal and is still one of the strongest.

Links were so critical to Google in the early days that the search engine was called Backrub before the name was changed to Google.

When the Google search engine was brand new, it was based exclusively on every page and every link on the Internet has a numerical value.

The value of pages was calculated based on the values of the links pointing to that page. The value of links was calculated based on the value of the webpage they originated on.

Below is a very simple example.

Let us suppose there is a webpage we’ll call X and it has a value of 100 and two outbound links.

Each link that originates on Page X has a value of 50. The value of each link is 50 because a page value of 100 divided by 2 (one for each link) causes each link to have a value of 50.

The value of page X is created by the links pointing to it. The total value of the incoming links add up to 100, in some combination. It could be one link with a value of 100, 100 links each of which has a value of 1, or any combination in between.