Short answer: A backlink is a link from one website to another. Search engines treat many links as votes of confidence, so links from relevant, trusted, genuinely-visited pages can help a page rank — but the quality and relevance of a link matter far more than the raw number you have.
What a backlink actually is
A backlink — sometimes called an inbound link or an external link — is simply a clickable link on someone else’s website that points to a page on yours. If a blog writes about accounting software and links to your pricing page, that link is a backlink to you. It is the digital equivalent of one publication citing another.
Search engines pay attention to these links because, in aggregate, they reveal something people say about a page rather than something the page says about itself. Google’s original PageRank concept, described in its founders’ 1998 paper, treated a link as a signal that one page found another worth referencing. That basic idea still underpins how links are used today, even though the modern system is far more nuanced.
Why backlinks matter for SEO
Google has publicly listed links among its ranking signals for years. The reasoning is intuitive: if many independent, credible sites reference a page, that page is more likely to be useful for the topic. Links help search engines in two practical ways — discovery (crawlers follow links to find new pages) and assessment (links are one input into how authoritative or relevant a page seems).
It is important to be honest about the limits here. Links are one signal among many, alongside content quality, relevance, page experience, and user behaviour. No single link guarantees a ranking, and SEO outcomes are probabilistic and slow to appear. Anyone promising a fixed position in exchange for a set number of links is overstating what links can do.
What separates a good backlink from a worthless one
Not all links carry the same weight. A link from a widely-read, topically-relevant page written by a real editor is worth far more than a link buried in a footer on a site nobody visits. The factors that tend to matter:
| Factor | Stronger link | Weaker link |
|---|---|---|
| Relevance | Same or adjacent topic to your page | Unrelated niche (e.g. a casino site linking to a bakery) |
| Editorial placement | Inside the body of a genuine article | Sitewide footer, sidebar, or comment spam |
| Real audience | Page that people actually read and visit | Page built only to host links |
| Trust of the linking site | Established, well-maintained domain | Thin, spun, or link-farm content |
| Link attribute | Natural editorial (followed) | Paid link not marked sponsored/nofollow (a violation) |
You will often see links described using third-party scores such as Domain Rating (DR) from Ahrefs or Domain Authority (DA) from Moz. These are useful directional estimates, but remember they are built by those companies — they are not Google metrics, and Google does not use them. Treat them as one lens, not the truth.
Dofollow, nofollow, and paid links
By default, a link passes ranking credit; this is often called a “dofollow” link. A link can also carry a rel attribute that tells search engines how to treat it. Google recognises rel="nofollow", rel="sponsored" (for paid or advertising links), and rel="ugc" (user-generated content). As Google explains in its documentation on qualifying outbound links, these are treated as hints when ranking.
The compliance line is simple and non-negotiable: any link you pay for, exchange, or otherwise arrange as advertising should be marked sponsored or nofollow. Buying followed links specifically to pass PageRank is against Google’s link spam policies and can lead to a manual action. If you want to understand the mechanics in depth, our dofollow vs nofollow guide walks through it.
How to earn backlinks honestly
The durable way to build links is to give other sites a genuine reason to reference you. That takes longer than buying links, but it does not put your site at risk. Common honest approaches:
- Create genuinely linkable assets — original data, clear explainers, free tools, or definitive guides that writers naturally cite.
- Digital PR and outreach — pitch relevant journalists and site owners a real story or resource, not a link request dressed up as flattery.
- Guest contributions — write useful articles for relevant publications where a link back is editorially warranted.
- Reclaim unlinked mentions — find places that already mention your brand and ask for the citation to become a link.
A useful mental test: would this link exist if search engines didn’t? If the answer is no, the link is probably the kind Google is trying to discount.
Measuring your backlink profile
You can see a sample of your links in Google Search Central’s Search Console under the Links report, or use third-party tools for a fuller picture. When you review links, look past the total count. Ask whether the linking pages are relevant, whether they get real visitors, and whether the anchor text looks natural. Our guide on how to evaluate backlink quality covers this in detail, and the broader link-building guide puts backlinks in the context of a full strategy.
If you would rather have relevant editorial placements handled for you, our link-insertion service focuses on contextual, disclosed placements on real, topically-relevant pages — no link farms, no guarantees we can’t keep.
The bottom line
Backlinks remain one of the most important off-page signals in SEO, but the value is concentrated in a minority of high-quality, relevant links. Chasing volume, buying followed links, or leaning on link farms tends to waste money at best and invite penalties at worst. Earn references from pages real people trust, disclose anything you pay for, and treat every link as a long-term investment rather than a shortcut.
Frequently asked questions
Do all backlinks help SEO?
No. A link from a relevant, genuinely-visited page carries far more weight than a link from a low-quality or irrelevant site, and spammy links can do nothing or even hurt. Relevance and real traffic matter more than raw counts.
How many backlinks do I need to rank?
There is no fixed number. Ranking depends on the query, your content, the competition, and dozens of other signals. A handful of strong, relevant links usually beats hundreds of weak ones, so focus on quality rather than a target count.
Can I buy backlinks?
You can pay for placement, but any paid link that passes ranking credit must be marked with rel="sponsored" or nofollow under Google's guidelines. Buying dofollow links to manipulate rankings is link spam and can trigger penalties.
What is the difference between a backlink and an internal link?
A backlink comes from a different website pointing to yours. An internal link connects two pages on the same site. Both matter, but backlinks are the ones treated as external votes of confidence.
How long do backlinks take to affect rankings?
Search engines have to crawl the linking page, then reassess your page. That can take days to months, and any effect is probabilistic — a good link improves your odds rather than guaranteeing a position.
Are nofollow backlinks worthless?
No. Nofollow links may not pass the same ranking credit, but they still send real visitors, build brand awareness, and often lead to genuine editorial links later. Google also treats the rel attribute as a hint rather than a strict rule.