A backlink is a link on someone else's website that points to yours. That is the whole definition. Everything else is about which ones are worth having, because the gap between a good backlink and a worthless one is enormous and most guides skip straight past it.
What a backlink is made of
Every link is a small piece of HTML, and each part of it carries information a search engine reads.
A link to your site looks like this in the page source: <a href="https://yoursite.com/guide" rel="nofollow">this SEO guide</a>. Four parts of that matter.
- The destination, the
href. Which page of yours receives the link. - The anchor text, the visible words. Here that is "this SEO guide". It tells search engines what the destination page is about.
- The rel attribute, optional. This is where the link says whether it is an endorsement.
- The page it sits on. Its topic, its authority and how many other links surround it.
Three things about the surrounding context matter as much as the tag itself: whether the linking page is about a related subject, whether a human editor chose to place it, and whether the link sits inside real content rather than in a footer or a comment.
The rel attribute, and what Google actually does with it
This is the part most explanations get slightly wrong, so it is worth being precise.
| Attribute | Written as | What it signals | Does it pass ranking value |
|---|---|---|---|
| Standard | no rel attribute | A normal editorial link | Yes |
| Nofollow | rel="nofollow" | Do not associate us with this page | Treated as a hint since March 2020 |
| Sponsored | rel="sponsored" | This link was paid for | Treated as a hint |
| UGC | rel="ugc" | User generated, such as a comment | Treated as a hint |
The important correction: since March 2020 Google has treated all three of those attributes as hints rather than directives. It decides case by case whether to use the link. That means a nofollow link from a major publication is not automatically worthless, and it is why "only dofollow links count" is outdated advice.
It also means the reverse. Adding rel="nofollow" to a paid link does not guarantee Google ignores it, so buying links and marking them nofollow is not the safe harbour people treat it as. Our fuller explanation of dofollow backlinks covers the distinction in more depth.
Why backlinks matter at all
Search engines needed a way to tell which of a million pages about the same topic deserved to be first. Links were the original answer, on the reasoning that a link is a person vouching for a page, and that reasoning still holds.
Three things a backlink does:
- It signals authority. A link from a site search engines already trust transfers some of that trust.
- It sends real people. A link on a page your customers read brings visitors regardless of any ranking effect.
- It gets you discovered. New pages are frequently found by crawlers following a link to them.
There is a fourth reason that is newer. AI assistants and answer engines choose which sources to cite, and being linked and cited across the web makes a site more likely to appear in those answers. That is a different mechanism from ranking, and it is increasingly where the traffic goes.
How to judge a backlink in under a minute
Most advice tells you to look for "high quality" links without saying how to tell. Here is a test you can run quickly on any link or link opportunity. We go through that test in more depth, with the thresholds we use, in our guide to judging backlink quality.
- Would this page send you a visitor even if search engines did not exist? If no, the link is probably worthless.
- Is the linking page about a related subject? A link from a plumbing blog to a plumbing supplier is worth many times a link from a general directory.
- Did a person decide to place it? Editorial links carry weight. Links you added yourself, in a profile, a comment or a directory listing, mostly do not.
- Does the page have real traffic? A site with no visitors and hundreds of outbound links is a link farm regardless of its domain metrics.
- How many other links are on that page? A page linking to 200 sites is spreading very little to each.
- Is the anchor text natural? A page where every outbound link uses exact commercial anchor text looks manipulated, because it is.
If a link fails three or more of those, it is not worth paying for and probably not worth chasing.
Quality against quantity
One link from a relevant, genuinely read publication will usually outperform fifty directory listings. This is not a slogan, it follows directly from how the signal works: authority is transferred proportionally, and a site with no authority has none to transfer.
The practical implication is that link counts are a poor way to measure progress. Referring domains, meaning the number of distinct sites linking to you, is a better one, and the quality of the top ten of those matters more than the total.
The main types, and what each is actually worth
| Type | How you get it | Honest value |
|---|---|---|
| Editorial mention | Someone cites your work unprompted | Highest. Also the hardest to manufacture |
| Guest post | You write for a relevant publication | Good, if the site has real readers |
| Digital PR or expert quote | You give a journalist a usable comment | Good, often from high authority sites |
| Resource page listing | Your page is added to a curated list | Moderate, and genuinely relevant |
| Broken link replacement | You offer a replacement for a dead link | Moderate, high effort per link |
| Link exchange | Two sites agree to link to each other | Depends entirely on execution, see below |
| Business directory | You submit your site | Low, but useful for local search |
| Forum or comment link | You post it yourself | Near zero, and often nofollow or ugc |
| Paid link on a link farm | You buy it | Negative. This is what link spam updates target |
The bottom two rows are where most wasted effort goes. Comment and profile links were worth something fifteen years ago and have not been for a long time.
What Google says about link schemes
Worth reading the actual position rather than the folklore. Google's spam policies name "link schemes" as a violation, and the definition covers buying or selling links that pass ranking signals, excessive link exchanges, and large-scale automated link building.
Two words in that do a lot of work: excessive, and schemes. A relevant site linking to you and you linking back because both links help readers is not a scheme, and never has been. Two sites agreeing to swap links purely to manipulate rankings, at scale, with no editorial reason, is.
The distinction is not the exchange itself. It is whether the links would survive a human editor asking why they are there.
Since the link spam updates began rolling out, the practical consequence of getting this wrong changed. Rather than penalising a site, Google increasingly just neutralises the links, so the money spent buys nothing at all. That is a quieter failure than a penalty and easier to miss.
Where link exchanges sit
Since this is the part most guides avoid, here is the straight answer. A reciprocal link between two genuinely relevant sites, placed in real content, is normal and has always existed. Bloggers in the same niche have linked to each other since blogs existed.
What crosses the line is volume without relevance: hundreds of swaps with unrelated sites, identical commercial anchor text, links dumped into a footer or a links page nobody reads.
This is the model Distribb's backlink exchange is built around, so treat this paragraph accordingly. It matches sites by topic and places links inside real articles rather than on a links page, which is the difference that decides whether an exchange is normal editorial behaviour or a scheme. The honest limitation: an exchange will never get you the kind of link a journalist gives you unprompted, and if you need authority links from major publications, digital PR is the route, not an exchange. We compare the options in our guide to the best backlink exchange platforms.
How to get backlinks, realistically
Four approaches that work, roughly in order of how much effort each takes per link earned. If you are doing this for a small business with no dedicated hours for it, our shorter list of ways to build backlinks for a small business narrows these four down to what fits.
Be a source for journalists. Reporters need expert comment on deadline. Providing a usable quote quickly is the most reliable way for a small site to get a link from a large one.
Publish something worth citing. Original data, a survey of your customers, a genuinely useful free tool or calculator. Pages that get linked without asking are almost always pages containing a number nobody else has. More approaches in that vein are collected in our guide to getting backlinks without paying for them.
Guest posting on relevant sites. Still works when the site has actual readers and you write something you would be happy to publish yourself. It stops working the moment it becomes volume submission to sites that accept anything. Where to pitch matters more than how many you pitch, and our list of guest posting blogs and services covers the sites that still send readers.
Replace broken links. Find dead links on relevant resource pages, offer your equivalent as the replacement. High effort per link, but the pitch is genuinely helpful, which is why the response rate holds up.
What none of these are is fast. If you want to understand the automated end of this properly, including where it works and where it does not, we cover how to build backlinks automatically. For the manual end of the same question, our guide to building high quality backlinks covers the tactics worth the hours.
Checking the backlinks you already have
You cannot improve a link profile you have not looked at. Three tools cover almost everyone.
Google Search Console is free and shows you the links Google itself knows about, under Links, then External links. Start here, because this is Google's own view rather than a third party estimate.
Ahrefs has the largest and freshest independent link index. Ahrefs Webmaster Tools gives you your own site's backlink profile free once you verify ownership.
Semrush covers backlinks alongside everything else, and its link gap report, showing sites linking to competitors but not to you, is the most directly actionable report in this category.
Whichever you use, look at three things: how many distinct domains link to you, whether the top ten are relevant to your subject, and whether anything obviously spammy has appeared. For most sites the answer to the last one is no, and the disavow file is best left alone unless you have a specific reason. Google has said repeatedly that most sites never need it, and a careless disavow removes links you were benefiting from. If you want to track this over time, we have a walkthrough of checking backlinks in Google Analytics too.
Frequently asked questions
How many backlinks do I need to rank?
There is no number. What matters is how your link profile compares with the pages currently ranking for your target term, which you can check directly in any link tool. For a low competition long-tail term the answer is sometimes zero.
Can I buy backlinks?
You can, and it violates Google's spam policies. The practical risk today is less that you get penalised and more that the links are simply ignored, so the money buys nothing. Paid placements marked rel="sponsored" are legitimate as advertising, and are not expected to pass ranking value.
Do nofollow links have any value?
Yes. Since 2020 Google treats nofollow as a hint rather than an instruction, and beyond that a nofollow link from a well-read site still sends real visitors and still contributes to people knowing you exist. Judging links purely by their rel attribute is outdated.
What is the difference between a backlink and an internal link?
A backlink comes from a different website. An internal link goes from one page of your site to another page of your site. Both matter, and internal links are the ones you fully control.
What is a referring domain?
The number of distinct websites linking to you, as opposed to the total number of links. Fifty links from one site count as one referring domain, and referring domains is the more meaningful number of the two.
How long do backlinks take to affect rankings?
Typically weeks to a few months. The link has to be crawled, evaluated and factored in, and the effect on a competitive term is gradual rather than a step change.
Are backlinks still important in 2026?
Yes, though less dominant than a decade ago and now doing a second job. Alongside rankings, links and citations influence which sources AI assistants draw on when they answer questions, which is a growing share of how people find things.
What is a toxic backlink?
A link from a site that exists to sell links, has no real audience, or is unrelated to everything it links to. In most cases these are simply ignored rather than actively harmful, which is why aggressive disavowing usually costs more than it saves.
The short version
A backlink is a link from another site to yours. The ones that matter come from relevant pages, are placed by a person, and would send you a visitor even if search engines vanished tomorrow.
If you only do one thing after reading this, open Search Console and look at which sites already link to you. Most people find one or two they did not know about, and those are usually the easiest relationships to build on. From there, our guide to getting more backlinks covers the tactics that grow that list deliberately.