If you have spent any time in conversations about SEO, you will have heard the word backlink. It is one of the most discussed concepts in the industry, one of the most misunderstood, and one of the most frequently used to justify work that ranges from genuinely valuable to actively harmful. Understanding what backlinks are, why they matter, and what good and bad link building looks like will help you hold any SEO provider to a proper standard of account.
The basic definition
A backlink is a link from one website to another. When a website publishes a piece of content and includes a clickable link that takes a reader to a page on your website, that is a backlink to your site. The term comes from the idea that the link points back to you from somewhere else on the web.
Backlinks are sometimes also referred to as inbound links or external links, and you may encounter all three terms being used interchangeably. They all mean the same thing: another website is linking to yours.
Why backlinks matter to Google
When Google’s founders developed the original algorithm that would become the foundation of the search engine, one of their core insights was that a link from one website to another could be treated as a signal of credibility. The reasoning was that if a website thought another page was worth linking to, that was a form of endorsement. The more credible websites that linked to a page, the more credible that page was likely to be.
This principle, known as PageRank after Google co-founder Larry Page, became one of the foundational elements of how Google ranked search results. Two decades later, despite enormous changes to the algorithm, links remain one of the most significant ranking signals in SEO.
A website with a strong backlink profile, meaning a collection of genuine links from credible, relevant sources, will typically rank better than a comparable website without one. Google treats those links as evidence that the website is a trusted and valuable resource in its field.
Not all backlinks are equal
This is where it gets more nuanced, and where understanding the detail matters practically.
A link from a well-regarded national publication, an industry association, a respected local business directory, or an authoritative website in your sector carries significant weight. Google recognises the credibility of the linking site and factors that into how much value it assigns to the link.
A link from a low-quality website that exists solely to sell links, a directory with no editorial standards, or a network of websites built specifically to manufacture backlinks carries very little value and can actively harm your rankings. Google has become very good at identifying unnatural link patterns, and websites caught with manipulative link profiles face penalties that can be severe and long-lasting.
The quality of a backlink is determined by several factors: the credibility and authority of the linking website, the relevance of that website to your sector, the context in which the link appears, and whether the link was placed editorially, meaning someone chose to include it because it was genuinely useful, rather than paid for or artificially arranged.
What good link building looks like
Earning high-quality backlinks is one of the most valuable things an SEO campaign can do for your website, and also one of the most labour-intensive. There are no shortcuts worth taking.
Good link building typically involves creating content that other websites genuinely want to reference. Useful guides, original research, expert commentary, and detailed resources all attract links naturally when they are good enough. This is sometimes called earning links, and it is the most sustainable form of link acquisition.
Digital PR is another legitimate approach. Proactively pitching stories, expert opinions, and data to journalists, bloggers, and industry publications can result in coverage that includes links back to your website. Done well, this builds both backlinks and genuine brand visibility.
Relationships with complementary local businesses, industry bodies, trade associations, and sector-specific organisations can also produce legitimate linking opportunities. A Lancashire manufacturer listed as a member of a trade body, a local business featured in a regional publication, or a professional services firm cited as a contributor to an industry resource are all examples of backlinks earned through genuine credibility.
What bad link building looks like
The SEO industry has a long history of manipulative link building, and some agencies still practise it. Buying links from websites that exist to sell them, participating in private blog networks where websites link to each other to inflate rankings artificially, and submitting to hundreds of low-quality directories are all approaches that carry significant risk.
Google’s ability to identify these patterns has improved steadily over many years. Websites that rely on manipulative backlink profiles are increasingly likely to be penalised, sometimes severely. The businesses that suffer when this happens are the clients, not the agencies that built the links.
If your SEO provider is vague about how they approach link building, or if the volume of links being built seems remarkably high without a clear explanation of where they are coming from, ask direct questions. You are entitled to a clear and honest answer.
What this means for your business
A strong backlink profile is built slowly, through genuine effort and genuine credibility. It cannot be manufactured quickly without taking risks that could undermine everything else your SEO is working to achieve.
The right question to ask about backlinks is not how many your website has, but how good they are. A handful of links from credible, relevant sources will do more for your rankings than hundreds of links from low-quality ones, and they will do so without putting your website at risk.
