Backlinks: What They Are and Why They Still Matter

A backlink is a hyperlink from one website to another. When another site links to your page, that link is a backlink to you. Search engines treat these links as signals of credibility, using them to assess whether a page is worth ranking highly for a given query.

That is the simple version. The fuller version is more interesting, and more commercially useful, because not all backlinks carry the same weight, not all of them help you, and the way Google uses them has evolved considerably over the past decade.

If you are building an SEO strategy and want to understand how backlinks fit into the broader picture, the Complete SEO Strategy hub covers the full landscape, from technical foundations to content and authority signals.

Why Do Search Engines Care About Backlinks?

The logic behind backlinks as a ranking signal is borrowed from academia. Academic papers cite other papers. The more times a paper is cited by credible sources, the more likely it is to contain something worth reading. Google’s original PageRank algorithm applied the same principle to the web: if many reputable sites link to a page, that page is probably worth surfacing.

The insight was sound. Before links became a core ranking signal, search engines were easy to manipulate with keyword stuffing and on-page tricks. Links introduced a layer of external validation that was harder to fake because it required other people to make an active choice to reference your content.

That external validation principle still holds. What has changed is how Google evaluates the quality of those links. Early SEO treated all links as roughly equivalent, and the industry responded by building links at industrial scale through directories, link farms, and paid placements. Google has spent the better part of fifteen years tightening its ability to distinguish links that reflect genuine editorial choice from links that were manufactured to game rankings.

The result is a more nuanced signal. A link from a respected industry publication, placed editorially within a relevant article, carries significantly more weight than a link from a generic directory that exists primarily to sell placements. The mechanics are more complex than early PageRank, but the underlying logic is the same: links that represent genuine endorsement matter.

What Makes a Backlink Valuable?

There are several factors that determine how much value a backlink passes to your site. Understanding them changes how you think about link acquisition, because it shifts the conversation from quantity to quality.

Domain authority. A link from a site that Google already considers authoritative carries more weight than a link from a new or low-authority domain. This is not a binary. Authority exists on a spectrum, and it is influenced by the quality and quantity of links pointing at that domain. Tools like Ahrefs and Semrush have their own proprietary metrics for approximating this, but they are estimates, not Google’s actual scores.

Topical relevance. A link from a site that covers the same subject matter as yours is generally more valuable than a link from an unrelated domain. If you run a logistics software business and a well-regarded supply chain publication links to your pricing guide, that link signals topical authority in a way that a link from a lifestyle blog cannot replicate.

Placement on the page. Links embedded within the body of an article, in context, carry more weight than links in footers, sidebars, or boilerplate sections. Editorial placement suggests the link was included because it was relevant to what the author was writing, not because it was templated across a site.

Anchor text. The clickable text of a link gives Google context about what the linked page is about. Anchor text that describes the content of the destination page is more informative than generic text like “click here.” That said, using the same keyword-rich anchor text across all your backlinks is a pattern that looks unnatural and can attract penalties. A healthy backlink profile has varied anchor text that reflects genuine editorial choice.

Follow versus nofollow. A standard link passes what SEO practitioners call “link equity” from the referring page to the destination. A nofollow link includes an attribute that historically told search engines not to pass that equity. Google has since said it treats nofollow as a hint rather than a directive, and other attributes like “sponsored” and “ugc” (user-generated content) have been introduced to add nuance. For most practical purposes, followed editorial links from authoritative sites remain the most valuable.

I spent several years running a performance-focused agency where SEO was one of the core disciplines. We had clients who came to us with thousands of backlinks and rankings that were deteriorating. When we looked at the profiles, the problem was usually the same: a history of low-quality link building that had accumulated over years, often from previous agencies chasing volume. Cleaning those profiles up was slow, unglamorous work. It rarely made for a good case study, but it was the right thing to do commercially.

What Are the Different Types of Backlinks?

Not all backlinks are created through the same mechanism, and understanding the different types helps you think more clearly about which are worth pursuing. Semrush has a useful breakdown of backlink types if you want a detailed taxonomy, but the practical distinctions worth knowing are these.

Editorial backlinks are placed by a writer or editor who chose to link to your content because it was useful or relevant. These are the gold standard. They are also the hardest to earn at scale, which is precisely why they carry weight.

Guest post backlinks come from articles you write for other publications, typically with a link back to your site in the author bio or within the content. Done well, with genuine editorial value, these can be legitimate. Done poorly, as a link-building factory producing thin content for low-quality sites, they are a waste of time at best and a liability at worst.

Directory and citation backlinks come from business directories, industry listings, and citation sites. These have limited SEO value in most cases, but they serve a purpose for local SEO and brand consistency. Government and institutional directories can carry more weight. Links from .gov domains are rare and difficult to earn, but they carry significant authority because of the domains they originate from.

Resource page backlinks come from pages that curate useful links on a topic. If a university or industry association maintains a list of recommended tools or reading materials and includes your site, that is a resource page link. These can be highly valuable depending on the domain.

Broken link backlinks are earned by finding broken links on other sites and suggesting your content as a replacement. It is a legitimate outreach tactic that provides genuine value to the site owner and earns you a link in return.

Paid backlinks are links purchased from other sites. Google’s guidelines explicitly prohibit buying links for the purpose of manipulating rankings, and its ability to detect paid link patterns has improved substantially. The risk is not theoretical. Sites have lost significant organic visibility because of paid link schemes, and recovering from a manual penalty is a painful, time-consuming process.

How Do Backlinks Affect Rankings in Practice?

Backlinks are one of the most significant ranking factors in Google’s algorithm, but they operate within a system of many signals. A page with excellent backlinks but poor content will not rank as well as a page that has both. A page with strong content but no external links will struggle to compete against established pages in competitive verticals.

The relationship is clearest in competitive queries. If you search for a high-value commercial term in a competitive industry, the pages that rank are almost always those with strong backlink profiles. Content quality gets you to the table; authority signals determine whether you sit at the head of it.

In less competitive niches, the picture is different. There are categories where thin content with a handful of decent links outranks more thorough content from sites with weaker profiles. This is one of the more frustrating realities of SEO from a content investment perspective, and it is why link building cannot be treated as an afterthought even when you are producing genuinely good work.

One thing I have seen consistently across the agencies I have run and the clients I have worked with: businesses that treat link acquisition as a one-time campaign rather than an ongoing programme tend to plateau. You earn a batch of links, see a rankings lift, then watch it erode as competitors continue building. The sites that maintain strong organic positions treat link acquisition as a continuous function, not a project.

There is also a growing body of evidence that backlinks influence performance in AI-driven search environments. Semrush’s research into backlinks and AI search suggests that sites with stronger link profiles are more likely to be cited in AI-generated answers. The mechanism is different from traditional ranking, but the underlying principle is the same: external validation signals credibility.

How Do You Assess the Quality of a Backlink Profile?

When I take on a new client with an existing SEO history, one of the first things I look at is the backlink profile. It tells you a great deal about how the site has been managed, what risks it carries, and what the realistic path to improvement looks like.

The metrics I look at first are not the headline numbers. A site with 50,000 backlinks is not inherently stronger than one with 5,000. What matters is the quality distribution. How many of those links come from domains that are themselves authoritative? How many come from sites that appear to exist solely to sell links? What does the anchor text distribution look like? Is it varied and natural, or is it heavily weighted toward exact-match commercial terms?

Tools like Ahrefs are useful for this kind of audit. Ahrefs has covered the nuances of backlink analysis in depth, and their Domain Rating and URL Rating metrics give you a reasonable proxy for link quality, with the caveat that they are proprietary estimates, not direct measures of Google’s assessment. I treat them as a useful lens, not a precise measurement.

Red flags in a backlink profile include: a sudden large spike in links from low-quality domains (often a sign of past link buying or spam), a high proportion of links from sites in unrelated industries, heavily over-optimised anchor text with the same commercial keywords repeated across many links, and a large number of links from sites that no longer exist or have themselves been penalised.

If you find a profile with significant toxic link patterns, Google’s Disavow Tool allows you to tell Google to ignore specific links. This is not something to use casually, and Google’s own guidance is that most sites do not need it. But in cases where there is a clear history of manipulative link building, it can be a necessary part of recovery.

For a broader look at how backlinks work and how to approach building them, Crazy Egg has a solid overview worth reading alongside your own audit process.

What Is the Difference Between a Backlink and an Internal Link?

A backlink, also called an inbound link or external link, comes from a different website. An internal link connects pages within the same domain. Both matter for SEO, but they serve different functions.

Internal links distribute authority around your own site and help search engines understand the structure and hierarchy of your content. Backlinks bring external authority into your domain from the outside. A strong internal linking structure helps ensure that authority flows to the pages you most want to rank, rather than sitting concentrated on your homepage or a handful of high-traffic articles.

The two work together. If a high-authority page on your site earns a strong backlink, internal links from that page can pass some of that authority to other pages on your domain. This is one of the reasons why hub-and-spoke content architecture, where a strong pillar page is supported by related articles and linked together tightly, tends to perform well in competitive verticals.

How Do You Earn Backlinks Without Paying for Them?

This is the question most people are really asking when they start looking into backlinks. The honest answer is that earning good links is hard, slow, and requires genuine effort. There is no shortcut that Google has not already seen and accounted for.

The most durable approach is to produce content that other people in your industry want to reference. Original research, detailed data, strong opinions backed by evidence, and genuinely useful tools all attract links organically over time. The challenge is that this takes longer than most marketing teams are willing to wait, and the causal link between publishing good content and earning links is not immediate or guaranteed.

Outreach accelerates the process. If you have produced something worth linking to, contacting relevant writers, editors, and site owners directly and explaining why your content would be useful to their readers is a legitimate tactic. The response rate is low. That is expected. The links you earn through genuine outreach are worth considerably more than those acquired through automated or bulk approaches.

Digital PR is another route. Producing data, reports, or commentary that journalists and bloggers want to cite generates editorial links at scale, but it requires either a dedicated team or an agency relationship with genuine media connections. I have seen this done well and done badly. Done well, it produces links from national publications and respected industry titles. Done badly, it produces press releases that nobody reads and links from syndication networks that Google largely ignores.

Partnerships and collaborations can also generate links naturally. Co-authored content, joint research, and cross-promotional activity between complementary businesses often produce links as a byproduct of the collaboration itself. These tend to be topically relevant and placed editorially, which makes them valuable.

When I grew an agency from around 20 people to over 100, one of the things that drove our own organic growth was a consistent investment in producing genuinely useful content for our industry. Not content designed to rank for keywords, but content that practitioners actually wanted to read and share. The backlinks followed because the content was worth referencing. It is a slower strategy than buying links. It is also the only one that compounds over time without introducing risk.

Are Backlinks Still Relevant as Search Evolves?

There is a recurring conversation in SEO about whether backlinks are losing their importance as Google’s algorithms become more sophisticated and as AI-driven search changes how results are surfaced. It is a fair question, and I think the honest answer is nuanced.

Backlinks are not declining in importance in absolute terms. What is changing is the context in which they operate. Google has become better at assessing content quality independently of links, which means links alone are less able to prop up weak content than they once were. But in competitive verticals, where content quality is broadly high across competing pages, link authority remains one of the most decisive differentiators.

The emergence of AI search adds another dimension. When AI systems generate answers, they draw on sources they consider authoritative. The criteria for what counts as authoritative overlap significantly with what makes a strong backlink profile: external validation from credible sources, topical depth, and a track record of being referenced by others in the field. The mechanism is different, but the underlying signal is similar.

I have judged the Effie Awards, which are among the most rigorous effectiveness awards in the industry. One thing that process reinforced for me is that the most durable marketing results come from building genuine credibility, not from gaming metrics. Backlinks, at their best, are a reflection of credibility. The sites that earn them through genuine editorial merit tend to maintain their positions. The sites that manufacture them tend to cycle through rankings lifts and penalties.

If you are building a long-term SEO programme, backlinks remain a foundational element worth investing in seriously. The tactics change. The underlying logic does not.

Everything covered here sits within the broader discipline of search engine optimisation. If you want to see how backlinks connect to technical SEO, content strategy, and competitive positioning, the Complete SEO Strategy hub brings those threads together in one place.

About the Author

Keith Lacy is a marketing strategist and former agency CEO with 20+ years of experience across agency leadership, performance marketing, and commercial strategy. He writes The Marketing Juice to cut through the noise and share what works.

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