Last Updated on 3rd May 2024

Google’s link based algorithms have been the backbone of search since the inception of the Google search engine and it could even be claimed that their early understanding and implementation of link graphs is what made Google stand out and become successful in the first place. Over the years Google has continued to refine various types of algorithms (there are many) to provide users with the most relevant and high-quality search results. Among these algorithms, link-based algorithms play a significant role in determining a website’s ranking in search engine results pages (SERPs). We look at Google’s link-based algorithms specifically and algorithms with link-based aspects, exploring key updates and implications for SEO.

The Birth of PageRank:

Google’s journey into link-based algorithms began with PageRank, named after Google’s co-founder Larry Page. PageRank revolutionized the way search engines ranked web pages by considering the quantity and quality of links pointing to a page as votes from both internal pages within the same website and external pages outside of a website. Introduced in the late 1990s, PageRank assigned a numerical value, or “PageRank score,” to each web page based on the inbound links it received. Pages with a higher PageRank score were deemed more authoritative and were likely to rank higher in search results. PageRank worked on a compounding scale with a range between 0 – 10 and each next level of ‘PageRank’ equated to double the value of the previous level of ‘PageRank’ and therefore representing a huge leap in authority at the higher levels of ‘PageRank’.

Penguin: Targeting Link Manipulation via Punitive Algorithmic Updates:

As the perceived importance of links in SEO grew, so too did the prevalence of link spam tactics aimed at manipulating and artificially inflating website rankings by SEOs. To combat this issue, Google launched a decimating punitive algorithm called the Penguin algorithm update in April 2012. Penguin specifically targeted websites engaging in manipulative link schemes, such as buying links or participating in link exchange networks and link farms. Websites caught violating Google’s quality guidelines faced penalties, including significant drops in search rankings.  At and around the same time as the initial Penguin algorithm update came a whole tranche too of punitive manual penalties for link manipulation and link buying.  Huge media agencies with many clients were were impacted and of course their clients, more importantly since ‘link budgets’ were the norm in the media agency SEO model with ‘link budgets’ being the proportion of an SEO retainer fee clients would pay for the sole purpose of buying links.

Penguin marked a significant shift in Google’s approach to link-based algorithms, emphasizing the importance of natural, high-quality, attracted links, over manipulative practices such as link buying and forcefully placing links on blogs and online editorial sites via paid link arrangements and ‘guest blogging’. SEO practitioners were forced to adopt more ethical link-building strategies focused on earning links through valuable content and genuine relationships with other websites.  NB: In theory this is the case but in practice many SEO agencies and SEO practitioners still partake in underhand ‘under the counter’ link buying (this is often under the thinly veiled guise of ‘digital PR’ or authority authorship fees), however it is likely far more of the links that people buy are now devalued or simply ignored by Google since further iterations of Penguin eventually moved towards an ‘ignore’ rather than ‘penalize’ approach to links.  Google now has decades of machine learning experience in classifying what a paid link or low quality forum or guest post linking looks like with high degrees of confidence.

Hummingbird: Understanding Contextual Relevance:

In September 2013, Google unveiled the Hummingbird algorithm update, which aimed to improve the search engine’s ability to understand the context and intent behind user queries. While not solely focused on links, Hummingbird had implications for link-based algorithms by prioritizing content relevance and semantic understanding.

Hummingbird placed greater emphasis on the overall context of a web page, including its content, structure, and the relationships between different pieces of information. As a result, SEO practitioners needed to focus on creating comprehensive, user-focused content that addressed the needs and intentions of their target audience. While links remained important, their relevance within the broader context of a website’s content became even more critical.

Panda: Quality Content and Link Evaluation:

While not predominantly a link-based algorithm, Google’s Panda update, first rolled out in February 2011, had implications for inbound link evaluation and quality. Panda targeted low-quality, thin content and content farms, aiming to elevate websites with high-quality, valuable content in search rankings.

The Panda algorithm update forced website owners to reevaluate their content strategies, prioritizing quality over quantity. For link-based algorithms, this meant that links from low-quality or spammy websites carried less weight, while links from authoritative, reputable sources became even more valuable.

E-A-T and Link Authority:

In recent years, Google has increasingly emphasized expertise, authoritativeness, and trustworthiness (E-A-T) as key factors in determining search rankings. While not a specific algorithm update, E-A-T has influenced how Google evaluates links and website authority.

Links from reputable, authoritative sources are now given greater weight, particularly for topics that require a high level of expertise or trustworthiness, such as health or finance (known as ‘your money or your life verticals’ because of the huge implications which poor search results could have upon search engine users money situation or life / health overall). Websites are encouraged to demonstrate their expertise and authority in their respective fields through high-quality content, expert contributors, and endorsements from other reputable sources.

The Future of Link-Based Algorithms:

As Google continues to refine its algorithms and adapt to changing user behaviors and technological advancements, the future of link-based algorithms remains dynamic. While links will likely continue to play a significant role in SEO, their importance may evolve alongside other factors, such as user signals, semantic understanding, and context and of course, everything increasingly moves towards a machine learning led blend of algorithms overall which is much more of a ‘black box’ concoction with less predictable results or ease of interpretation.  Google do increasingly state that links are reducing in importance in the determination of rankings and Google’s overall ability to rank webpages but they are still votes from other pages (either internally (within your own site), or externally (from other websites)), it’s just the value of the votes may be worth less than they were previously and they are now ‘one of very many things’.