A backlink is a link from one website to another. When a credible website links to yours, it passes a signal to Google that your page is worth referencing — a digital endorsement of your content's authority. Backlinks remain one of the top three ranking factors in Google's algorithm, but the 2024 updates fundamentally changed which backlinks help, which are neutral, and which actively harm a site.

The era of counting links is over. What Google measures now is the quality, relevance, and editorial context of the sites linking to you. A single link from a respected industry publication outperforms hundreds of links from low-authority directories or private blog networks — and those low-quality links now carry real penalty risk after the March and May 2024 spam updates.

How does Google decide a backlink is valuable?

Google evaluates backlinks on several dimensions simultaneously. Authority: does the linking site have real traffic, real audience, and earned trust? Relevance: is the linking site topically related to your site? Editorial context: was the link placed naturally within real content, or was it a footer link, sidebar link, or paid placement? Anchor text: does the anchor text match the topic of the linked page, and does the anchor text distribution across all your backlinks look natural?

What changed in 2024's spam updates?

Google's March 2024 spam update explicitly targeted three categories that had become common manipulation vectors: expired domain abuse (buying old domains with inherited authority and redirecting them as link sources), scaled content abuse (building sites purely to host guest posts and generate links), and site reputation abuse (major sites allowing third-party content as a backdoor for link injection). These were all practices that had functioned as grey-to-black hat link schemes for years — in 2024, Google moved to algorithmically devalue or penalise them at scale.

In 2024, a hundred bought links is a liability, not an asset. Google can identify link schemes with far more precision than it could in 2021, and the downside has never been steeper.

How do you earn backlinks that actually help?

Legitimate link building is essentially digital PR: creating content, data, or tools that authoritative sites want to reference, and then building relationships that get your work in front of the people who can link to it. This is slower than buying links, but it compounds — links earned through genuine authority tend to be joined by more links over time, because credibility attracts credibility.

Does the number of backlinks still matter at all?

Volume still matters — but as a distant secondary signal after quality. Ahrefs has consistently reported that top-ranking pages tend to have more referring domains than lower-ranked competitors, all else being equal. But the causality runs through quality: a page that earns links naturally accumulates more of them over time. Trying to manufacture volume without quality no longer produces the same outcome it did pre-2024. The March 2024 core update confirmed that Google's ability to assess link quality improved meaningfully — which means the quality gap matters more now than it did before.

For more on what underpins ranking authority in 2024, read our breakdown of E-E-A-T and why Google rewards it. And to understand how the cost of SEO maps to link-building work, that guide covers how agencies price these services.

Frequently asked questions

Should I disavow old bad links I didn't build?

Google's official guidance is to use the disavow tool only if you have a manual action (penalty) caused by unnatural links, or if you are confident a significant portion of your backlink profile is spammy. For most sites, Google's algorithms already discount low-quality links; indiscriminate disavowing can remove links that are helping. Use it surgically, not broadly.

How long does it take for a new backlink to affect rankings?

Google must crawl and process the linking page first, which can take anywhere from days to weeks. After processing, the signal is incorporated in the next time your site's rankings are recalculated — which happens on a rolling basis. In practice, meaningful backlinks from strong domains can show ranking movement in two to six weeks.