SEO is based on 3 pillars: technical SEO, content (user search intent based content) and backlinking.

Backlinking or netlinking is the discipline of acquiring and optimising links from authoritative content.

But what makes a perfect link?

Let's start at the beginning: PageRank

PageRank (also known as PR) is a link analysis algorithm used by Google Search to rank web pages in its search engine results. It is one of several algorithms used by Google, but is probably the easiest to understand. PageRank is a way of measuring the importance of web pages.

According to Google:

PageRank works by counting the number and quality of links to a page to determine a rough estimate of how important the website is. The underlying assumption is that more important websites are likely to receive more links from other websites.

We could explain the mode of calculation:

Or the graphical way Google presented it:

But I decided to focus on some practical rules to better understand the influencing parameters:

  1. 1.

    Links from more popular pages pass more value.

  2. 2.

    Links within unique main content pass more value than header/footer/menu links.

  3. 3.

    Links higher up in the main content pass more value.

  4. 4.

    Links with relevant anchor text pass more value. Forget about "click here", "learn more" buttons or clickable images.

  5. 5.

    The anchor (the clickable text) carries semantic information about the destination page. (Tip: I encourage the use of the meta keyword field to provide some information about the desired anchor for a page).

  6. 6.

    Links from unique domains are more important than links from previously linking sites (domain diversity).

  7. 7.

    External links are more influential than internal links.

  8. 8.

    Links from sites closer to a trusted seed set may pass more value.

  9. 9.

    Links from topically relevant pages carry more weight.

  10. 10.

    Links from fresh (or regularly updated) pages can pass more value than links from stale pages.

  11. 11.

    The rate of link growth can overwhelm other signals.

  12. 12.

    Google may devalue and/or ignore spam and low quality links.

  13. 13.

    The influence of a link may persist even after it disappears.

  14. 14.

    Sites that link to authoritative content may count more than those that do not (hint: not to favour a potential semantic competitor, I encourage links to Wikipedia pages).

  15. 15.

    Sites that link to spam may devalue the other links they host.

  16. 16.

    Nofollow links aren't followed, but may have value in some cases.

  17. 17.

    Javascript links only pass value when rendered by Google.

  18. 18.

    If a page links to the same URL more than once, the first link will take precedence.

  19. 19.

    Robots.txt and meta robots affect how and whether links are seen.

  20. 20.

    Disavowed links don't pass any value.