When Site A links to your web page, Google sees this as Site A endorsing, or casting a vote for, your page. Google takes into consideration all of these link votes (i.e., the website’s link profile) to draw conclusions about the relevance and significance of individual web pages and your website as a whole. This is the basic concept behind PageRank.
When a website links to your site, or when you link internally from one of your pages to another, the link passes PageRank points. This passing of PageRank points is also commonly called “link juice” transfer.
The amount of link juice passed depends on two things: the number ofPageRank points of the web page housing the link, and the total number of links on the web page that are passing PageRank. It’s worth noting here that while Google will give every website a public-facing PageRank score that is between 1 and 10, the “points” each page accumulates from the link juice passed by high-value inbound links can – and do – significantly surpass ten. For instance, web pages on the most powerful and significant websites can pass link juice points in the hundreds or thousands. To keep the rating system concise Google uses a lot of math (ask me in the comments if you want to hear about it) to correlate very large (and very small) PageRank values with a neat and clean 1–10 rating scale.
How Link Juice is Passed
Think of it this way: every web page has a limited amount of link juice it can pass, and the top of that limit is the total PageRank points that page has accrued. So, a web page with 20 accrued PageRank points cannot pass more than 20 points of link juice per page. If a page with 20 PageRank points links to one other page, that one link will transfer the full amount of link juice to that one other web page. But if a page with 20 PageRank points links to five web pages (internal or external), each link will only transfer one-fifth of the link juice. Google applies a decay value to every pass, so the actual numbers will be a little less than our diagram shows below. But to explain the PageRank concept simply, the formula is PR points divided by number of on-page links, or in this case, 20 divided by 5:
What if you want to link to several resources to aid user experience, but you don’t want to dilute your link juice transfer? You can tell Google not to pass PageRank by amending some links with a rel=”nofollow” tag. So if you have a PageRank 18 web page that has 4 links on a page and three of those links have rel=”nofollow” tags, the one link that doesn’t have a rel=”nofollow” tag will get the full 18 points of link juice.
Transferring PageRank/Link Juice with Internal Linking
You can help Google see pages of your website as subject matter authorities by linking to your own important pages from related articles. For instance, if you have an article called How To Do Keyword Research, you can help reinforce to Google the relevance of this page for the subject/phrase “keyword research” by linking from an article reviewing a keyword research tool to your How To Do Keyword Research article. This linking strategy is part of effective siloing, which helps clarify your main website themes.