Link signals
What are backlinks and why do they matter for SEO?
Links are how the web was built and how search engines still find most of what they index. That is the whole reason a link from somebody else is worth something.
What are backlinks and why do they matter for SEO?
A backlink is a link on someone else's website that points to a page on yours. Search engines follow links to discover pages, and they treat links from established, relevant sites as one signal of how prominent and trustworthy a page is.
Backlinks are one input inside off-page SEO rather than the whole of it, and buying or exchanging links for ranking purposes is named as link spam in Google's published policies, which is one reason the real value of any individual link is not measurable from outside Google.
The plain definition, and the one word that matters
A backlink is simply a link pointing at you from a site that is not yours. The load-bearing word is not link. It is someone else's.
An internal link, from one page of your site to another, is something you control completely. It is genuinely useful: it helps search engines find pages and tells them how your content is organised. But it carries no outside opinion, because you wrote both ends of it.
A backlink is different because a third party chose to point at you. That choice is the signal. A search engine cannot verify that you are good at what you do, but it can observe that a trade association, a supplier, a local news site and three respected blogs in your field all decided to send people to your page.
This is also why the phrase link building sits uneasily. The links that carry meaning are the ones somebody gave you. The ones you built for yourself are, by definition, back to being something you control, which is exactly what Google's policies are written to discount.
How a link actually gets used
Before a link is a ranking signal it is a road. Search engines find most new pages by following links from pages they already know.
Google's documentation is specific about what counts as a followable link: an anchor tag with an href attribute pointing at a real URL. A clickable element wired up with JavaScript, a button that triggers a script, or an href set to a fragment or a javascript call is not something a crawler can follow.
That technicality catches people out on their own sites more often than on other people's. A navigation menu built entirely in script can leave whole sections of a site undiscoverable, which looks like a content problem and is actually a markup problem.
The second job of a link is context. The visible link text, the sentence around it and the topic of the page it sits on all tell a search engine what the destination is likely to be about. A link reading read more tells it nothing. A link reading porcelain veneer aftercare tells it a great deal.
What makes one link worth more than another
Not all links are equal, and the differences are mostly observable without any tool at all.
- Relevance: a link from a site about your field means more than a link from a site about nothing in particular.
- Editorial choice: a link a writer chose to include reads differently from one placed in a footer, a widget or a signature.
- Placement: a link inside the body of an article sits in context, whereas a link in a sidebar repeated across ten thousand pages does not.
- Anchor text: the visible words describe the destination, and exact-match commercial phrases repeated at scale are one of the clearest fingerprints of a paid campaign.
- Attributes: rel values of nofollow, sponsored or ugc tell Google not to pass ranking signals, and paid or user-generated links are supposed to carry one of them.
See the full checklist: What makes one link worth more than anotherHide the full checklist: What makes one link worth more than another
- Crawlability: if the link is not a real anchor tag with an href, it cannot be followed at all, whatever else is true about it.
- The site around it: a page that exists to host links, with no readership and no editorial standard, is recognisable as such.
- Referral value: the most reliable question is whether real people will click it, because a link that sends actual customers was worth having even if it passes nothing.
That last item is the only one with a business answer attached. If a link would send you a customer, it is worth pursuing regardless of what any tool scores it.
Buying and exchanging links is against Google's policy
Google's spam policies for web search name link spam explicitly, and the definition covers buying or selling links for ranking purposes, excessive link exchanges, and large-scale article campaigns built for links rather than readers. This is published policy, not folklore, and it has been stable for years.
Anything where value changed hands falls under it: money, free product, a discount, a reciprocal placement. Google's stated remedy is not secrecy, it is disclosure. Paid and sponsored links are supposed to carry the sponsored attribute, user-submitted links the ugc attribute, and either way no ranking signal is meant to pass.
Read the full breakdown: Buying and exchanging links is against Google's policyHide the full breakdown: Buying and exchanging links is against Google's policy
The commercial reason to take it seriously is not fear of a penalty letter. It is that you cannot tell whether you bought anything. Link value is not measurable from outside Google, which means a vendor selling links is selling an outcome neither of you can inspect, against a policy that says the outcome should not occur.
Third-party authority scores deserve the same scepticism. However they are branded and whatever scale they use, they are estimates built by a vendor crawling the web and modelling what they think matters. They are reasonable for comparing two sites at a glance. They are not Google metrics, Google publishes no equivalent, and a score going up is not evidence that search performance improved.
Three ways links arrive, and how they age
The difference is not moral, it is practical: these three behave completely differently over time.
| Item | What it looks like | Cost | How it ages |
|---|---|---|---|
| Earned | A journalist, supplier or association links to something because it is useful | Slow, and mostly the cost of making something worth linking to | Improves, because the page it sits on keeps being read |
| Built | You ask: partners, memberships, stockist pages, a corrected citation | Time and relationships | Stable, as long as the relationship and the page survive |
| Bought | A placement sold as a link, on a site that sells links | Cash, repeatedly | Against Google's policy, unmeasurable, and gone when you stop paying |
Almost every business already has an unworked list in the middle row: suppliers, associations, chambers, charities, partners and franchisors. It is unglamorous and it is real.
You do not build links, you build reasons
The only repeatable way to earn links is to publish something a specific person would be professionally embarrassed not to reference.
Generic content earns nothing, because there is no reason to point at a page that says what forty other pages already said. What gets referenced tends to be one of a few things: original data nobody else has, a genuinely complete explanation of a confusing process, a free tool or calculator, or local knowledge that only someone actually operating in that place would know.
Then you have to tell someone. A page nobody has seen cannot be linked to. Telling the people who would find it useful, by name, one at a time, is unfashionable, slow and the only honest version of outreach.
Set the expectation correctly. This produces a handful of links, not hundreds, and it takes months. It also produces something that keeps working, which mass placement never does.
How to look at your own backlinks for free
Google Search Console has a Links report and it is the only view of your backlinks that comes from Google itself.
- Open the Links report and read Top linking sites: this is who points at you most often, ordered by number of linking pages.
- Read Top linked pages: if the answer is only your home page, nothing you published has been worth referencing yet.
- Read Top linking text: the anchor words used most often, which is where an aggressive past campaign becomes visible immediately.
- Ask of every top linking site: would I be comfortable if a client asked me why that site links to me.
- Compare against reality: if you have partners, suppliers or associations who should be linking to you and are not, that is a list to work through, not a tool to buy.
- Ignore the disavow tool unless you have received a manual action for unnatural links or have strong reason to believe one is coming. Its documented use is narrow, and removing links that were helping is a real risk.
If a vendor shows you a backlink report that looks nothing like Search Console's, remember which of the two is produced by the company running the index.
Related answers
Backlinks are one signal inside a wider category. These pages cover the rest of it and what sits underneath.
What is off-page SEO?
The category backlinks belong to, including citations, reviews, brand mentions and brand search demand.
What is off-page SEO?What is technical SEO?
Why a link is wasted on a page that cannot be crawled, and how to check that yours can.
What is technical SEO?Content that ranks and gets cited
What a page needs to be worth referencing, which is the only durable input to earning links.
Content that ranks and gets citedThe local SEO guide
Where links fit alongside listings, reviews and proximity for a business serving a real geography.
The local SEO guideWondering whether your link profile is helping or hurting?
We will read what Search Console actually shows and tell you which relationships are worth working, without selling you a placement.
Straight answers.
How many backlinks do I need to rank?
There is no number, and anyone who quotes one is guessing. Links are one signal among many, their value varies enormously by source, and nothing outside Google can measure what an individual link contributed.
A more useful question is which sites link to the pages currently beating you, and whether any of those relationships are available to you too. That produces a shortlist you can act on instead of a target you cannot verify.
Are nofollow links worthless?
No, though they are not doing the ranking job people expect. The nofollow, sponsored and ugc attributes tell Google not to pass ranking signals through the link.
They still send real visitors, still put your name in front of an audience, and still contribute to people searching for you by name later. A nofollow link from a publication your customers read is more valuable than a follow link from a site nobody visits.
Can bad backlinks hurt my site?
Usually Google simply ignores links it does not trust, which is why most sites never need to act. The exception is a manual action for unnatural links, which appears in Search Console and tells you directly.
The bigger practical risk is spending money on links that do nothing, then attributing a later ranking change to them. That misreads the cause and encourages more spending in the same direction.
What is the difference between a backlink and an internal link?
A backlink comes from someone else's website. An internal link goes from one page of your site to another page of your site.
Internal links are entirely within your control and they matter more than most people think: they help search engines discover pages and show how your content is organised. They just do not carry an outside opinion, which is the part a backlink supplies.
Do I need a link building service?
Only after the cheaper work is done. Correct listings, a complete Google Business Profile, a steady stream of first-party reviews and pages worth referencing all come first, and all are more controllable.
If you do buy help, ask what exactly is being delivered. Outreach to named, relevant organisations is legitimate work. A monthly quota of placements on sites that sell placements is buying links, whatever it is called on the invoice.
Do backlinks matter for AI search and assistants?
Plausibly, and the mechanics are not fully documented. Assistants draw on published sources, and being referenced by well-regarded sites makes a business easier to describe accurately.
What nobody can honestly offer is a guaranteed citation in an AI answer. How these systems select sources is not published in enough detail for anyone to promise it.
Where this comes from.
Primary documentation and published research behind the guidance on this page.
- Google Search Central: Spam policies for Google web search (opens in a new tab)Includes the link spam policy that covers bought and exchanged links.
- Google Search Central: Make your links crawlable (opens in a new tab)
- Google Search Central: Google Search Essentials (opens in a new tab)
- Google Search Console Help: About Search Console (opens in a new tab)
- Google Search Central: Creating helpful, reliable, people-first content (opens in a new tab)Google's published self-assessment questions for content quality and experience.
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