Backlinks

What are backlinks and why they are a Google ranking metric?

Backlinks have been at the core of Google’s ranking algorithm since the search engine’s inception. They remain one of the most influential ranking signals, playing a critical role in how Google evaluates the authority, relevance, and trustworthiness of a website. However, the journey of backlinks as a ranking metric hasn’t been without challenges. Over the years, Google has had to adapt its algorithms to combat manipulation and ensure that backlinks reflect genuine recommendations rather than artificial boosts.

What are backlinks?

Backlinks, also known as inbound links or incoming links, are links from one website to another. For example, if another website links to your site, that’s a backlink for you.

Google considers backlinks as votes of confidence from one website to another. The more high-quality backlinks a site has, the more likely it is to be seen as a credible, authoritative source on a given topic. However, not all backlinks are created equal. A link from a highly reputable site, such as a government or university domain, carries much more weight than a link from a little-known or spammy website.

Backlinks are one of the key components of Google’s PageRank algorithm, which measures the importance of web pages based on the quantity and quality of links pointing to them.

Why did Google make backlinks a ranking metric?

The concept of backlinks as a ranking factor dates back to 1998, when Larry Page and Sergey Brin, the founders of Google, published their research paper titled “The Anatomy of a Large-Scale Hypertextual Web Search Engine”. This paper introduced PageRank, Google’s original algorithm, which assigned importance to web pages based on the quantity and quality of links pointing to them.

At the time, most search engines ranked pages based solely on keyword relevance. However, Page and Brin recognised that links could serve as a signal of trust and authority, similar to academic citations. The more a page was “cited” by other reputable sources, the more valuable it likely was.

This idea became the foundation of Google’s ranking system and helped Google outperform its competitors in delivering more accurate and relevant search results.

Here’s why backlinks became such a critical ranking metric:

Backlinks are a way for Google to gauge the quality and trustworthiness of content.

The history of backlink manipulation

While backlinks have always been a core part of Google’s ranking system, SEO practitioners quickly realised their importance and began exploiting them. This led to widespread link manipulation, such as buying links, using link farms, and creating spammy directory submissions to artificially boost rankings.

To counteract this abuse, Google introduced several key updates to improve how it evaluates backlinks and reduce the impact of low-quality, spammy links on search results.

1. The Penguin Update (April 24, 2012)

One of the most significant updates in the history of backlinks was Google Penguin, which launched in April 2012. The Penguin update specifically targeted websites that manipulated backlinks to boost their rankings.

Penguin penalised sites that:

• Participated in link schemes (buying or selling links to manipulate PageRank)
• Had unnatural link profiles (links from irrelevant or low-quality sites)
• Used anchor text over-optimisation (excessive use of exact-match keywords in links)

Following Penguin, many websites saw their rankings plummet overnight, and the update fundamentally changed the way SEOs approached link-building. The focus shifted from quantity to quality.

2. Disavow Tool (October 2012)

In the same year as Penguin, Google introduced the Disavow Tool, allowing webmasters to disown toxic backlinks that could harm their rankings. This was a response to SEOs who had accumulated large numbers of spammy links in the pre-Penguin era and needed a way to clean up their link profiles.

3. Ongoing Penguin updates (2016 and Beyond)

In 2016, Penguin became part of Google’s core algorithm and now runs in real time. This means Google is constantly evaluating backlinks, and sites no longer have to wait for a major update to recover from a penalty.

Key backlink-related updates timeline

How to build high-quality backlinks

Building backlinks today requires a strategic and ethical approach. Here are practical tips to help you earn valuable backlinks that boost your rankings without risking a penalty.

1. Create high-quality, shareable content

The most effective way to earn backlinks is by creating valuable content that people naturally want to share and reference. This can include:

• In-depth guides and resources
• Original research and data
• Infographics and visuals
• Expert interviews or case studies

When your content provides real value, other websites are more likely to link to it as a helpful resource.

2. Build relationships with other websites

Backlinks often come from genuine relationships. Networking with relevant industry sites, bloggers, and journalists can lead to natural backlinks.

• Guest posting: Offer to write valuable content for other sites in your niche.
• Outreach: Reach out to websites that might find your content valuable and suggest they link to it.
• PR and media mentions: Get your brand featured in news articles, industry roundups, and interviews.

3. Monitor Your backlink profile

Regularly check your backlink profile to ensure you’re not accumulating toxic links that could harm your rankings. Use tools like:

• Google Search Console
• Ahrefs
• SEMrush

If you spot harmful links, use Google’s Disavow Tool to disassociate your site from them.

4. Avoid black-hat tactics

It’s important to avoid manipulative link-building tactics that could trigger a penalty, such as:

• Buying or selling links
• Using link farms
• Excessive link exchanges

Focus on earning links through relevance and quality, not manipulation.

Why backlinks still matter

Despite the rise of new ranking factors like user experience and Core Web Vitals, backlinks remain a fundamental part of Google’s algorithm. They serve as a powerful signal of authority and trustworthiness, helping Google determine which sites deserve to rank higher in search results.

Quality over quantity is now the guiding principle. By creating valuable content, building genuine relationships, and maintaining a healthy link profile, you can leverage backlinks to boost your site’s authority and improve your search rankings in a sustainable way.