Backlinks: How to Judge Quality and Earn Them
Backlinks are links from someone else's website to yours. They were the first signal Google used to judge relevance in 1998, and they still are – only no longer as a count, but as a quality judgement. This guide covers how to recognise a valuable link, how to vet a source before you reach out, and which link building methods still work.
1. What is a backlink?
A backlink – also called an inbound link – is a reference from another domain to a URL on your site. From the linking page's perspective it is an outbound link; from yours it is inbound.
For a link to count as a backlink, three technical conditions have to hold:
- A real
<a>element with anhref: click handlers on<span>or<button>are not links to a search engine. - A crawlable source page: if the linking page is set to
noindexor blocked by robots.txt, the signal does not arrive. - A resolvable target: if the link points to a
404URL or into a redirect loop, it is wasted.
How the signal travels once those hold is covered in the guide to link juice & link equity. This guide is about the question that comes first: which link is worth anything at all?
2. Why backlinks still count
The core idea is unchanged: a link is a recommendation someone makes voluntarily and stakes their own visibility on. That is harder to fake than any on-page signal.
Three things have shifted significantly, though:
- From volume to quality. Until roughly 2012, sheer numbers worked. Since the Penguin update and the link spam updates from 2022 onwards, manipulative links are usually devalued automatically – they do not hurt, they simply do nothing.
- From domain to page. What increasingly matters is which page links to you and in what context, not how strong the domain is overall.
- From ranking to citability. In AI answer systems links do double duty: as a classic signal, and as evidence that others treat a source as worth citing.
An important caveat: backlinks are a strong signal but no substitute for relevance. A page that fails to serve the search intent will not rank even with good links. Conversely, an excellent page with no external links at all can rank very well in low-competition niches.
3. The ten quality markers of a backlink
Check them in this order – the top items outweigh the lower ones:
| Marker | What to look at | Weight |
|---|---|---|
| Topical relevance | Does the linking page cover the same subject? | Very high |
| Editorial nature | Given freely, or paid, exchanged, self-placed? | Very high |
| Position in the document | Main body, author box, sidebar or footer? | High |
| Indexability of the source page | Is the linking page itself in the index? | High |
| rel attribute | nofollow, sponsored, ugc or none? |
High |
| Anchor text | Descriptive, generic or over-optimised? | High |
| Number of other links on the page | One link among 8, or among 200? | Medium |
| Actual traffic to the source page | Do humans read the page? | Medium |
| Target URL | Homepage or the matching deeper page? | Medium |
| Domain strength | Reputation and link profile of the source | Lower than most people assume |
That last point surprises people: domain strength is deliberately at the bottom. In practice a contextual link from a topically relevant specialist article on a mid-sized site outperforms a footer link from a very strong but unrelated domain.
4. Link types and their realistic value
| Type | Example | Value | Risk |
|---|---|---|---|
| Editorial contextual link | A specialist article cites your study | Very high | None |
| Digital PR / press coverage | Media pick up your data | High | None |
| Resource and tool lists | A roundup of useful utilities | High | None |
| Guest post with editorial review | Expert piece in a trade outlet | Medium to high | Low |
| Association, chamber, university | Vetted membership listing | Medium | None |
| Edited industry directory | Reviewed entry | Low to medium | Low |
| Profile and signature links | Forum profile, social media bio | Very low | Low |
| Bulk directory, no review | Automated submission | None | Medium |
| Paid link without disclosure | Bought post without sponsored |
None | High |
| Private blog networks (PBN) | A network of satellite sites | None | Very high |
5. Vetting a link source before you reach out
Six checks that take about five minutes together and filter out most bad sources:
- Is the page in Google's index? Look the URL up with
site:. Unindexed source pages pass no signals. - Does the domain rank for its own topics? Test two or three obvious queries. A domain with no rankings of its own has no visibility to pass on.
- What does the topic mix look like? A site writing about loans, crypto, gambling and pets is a link vendor.
- How many outbound links does the specific page carry? With 150 external links on one page, the share per link is negligible.
- Are all outbound links
nofollow? Some publishers applynofollowacross the board. That is legitimate, but it changes what the placement is worth. - Is there a visible price list? If so, it is a paid link and must be marked
sponsored– otherwise the placement breaches Google's policies.
6. Methods that work
They all share one trait: they give other people a reason to link that would not exist without you.
- Publish original data. Analyses from your own records – price trends, usage patterns, industry benchmarks. Anyone who wants to cite the number has to link you. This is the most reliable method there is.
- Build tools and calculators. A genuinely useful utility gets linked from forums, blogs and roundups for years, with no further effort.
- Original explanatory content. A guide that demonstrably explains a topic better than anything available becomes the reference.
- Digital PR with a real angle. A survey, an analysis, a position on an industry development. One angle produces many different domains at once.
- Professional visibility for your people. Talks, interviews, expert contributions. Links to author profiles also strengthen the entity behind the brand.
- Broken link reclamation. Find
404pages on your topic on other people's sites and offer your content as the replacement. - Collect unlinked mentions. Search for mentions of your brand without a link and ask politely. Conversion is high, because the editorial decision has already been made.
7. Methods that no longer work
- Bulk directories and article directories. Ineffective for over a decade.
- Comment and forum spam. Almost always
nofolloworugc, plus reputational damage. - Link exchange at scale. Reciprocal patterns are trivial to detect programmatically. A single link to a partner is harmless; a systematic exchange network is not.
- PBNs. High risk for little benefit.
- Undisclosed paid links. A breach of the spam policies – and in most jurisdictions also an advertising disclosure issue.
- Widget and footer links across many sites. The classic sitewide pattern with minimal effect.
- Mass-produced guest posts. Bulk content without editorial review is recognised as such.
Legal note: paid placements – including product reviews in exchange for goods – must be disclosed as advertising in most jurisdictions, including Germany. That is consumer and competition law, independent of SEO. For specific partnerships, get legal sign-off before signing.
8. What Google's link spam policies actually say
The scope is narrowly defined: prohibited are links whose primary purpose is manipulating rankings. Google names, among others:
- buying or selling links that pass ranking signals – with money, goods, services and other considerations treated equally
- excessive link exchange
- automatically generated links
- links in large-scale distributed guest posts with heavily keyword-optimised anchor text
- links from advertising placements without
sponsoredornofollow
The response matters: usually there is no penalty, only devaluation. The links simply do nothing. A manual action for unnatural links is the exception today – and would appear in Search Console under "Manual actions". How to handle that is covered in the section on link profile warning signs.
9. Measuring and monitoring backlinks
| Source | Strength | Limitation |
|---|---|---|
| Search Console, Links report | Real Google data | Row cap, partly aggregated, no full export |
| Bing Webmaster Tools | Free, its own index | Different data basis from Google |
| Backlink tools | History, anchor texts, competitor comparison | Only their own crawl |
| Server referrer data | Shows links that produce real clicks | Captures only links people use |
Useful monitoring needs only four figures: new referring domains per month, lost referring domains per month, share of topically relevant sources, and distribution across target URLs. Everything beyond that is reporting decoration.
10. Reclaiming lost backlinks
The fastest gain in all of off-page work, because the links already exist:
- Find backlinks pointing to
404URLs. Export your backlinks and check the target status codes. Every dead target URL is wasted effect. - Redirect them appropriately. A
301to the topically equivalent page – not a blanket redirect to the homepage. - Resolve redirect chains. Old backlinks often point at URLs that get redirected two or three times.
- Ask about removed links. If a link disappeared during a rewrite, a short factual enquiry is worth the effort.
- Check image usage. If your graphic is used but not credited, that is the easiest possible reason for an outreach email.
11. Backlink audit checklist
- Merge referring domains from Search Console and one tool.
- Check the status code of every target URL and redirect
404targets. - Resolve redirect chains on backlink targets.
- Assess the top 30 sources qualitatively: relevance, position, rel attribute.
- Determine the split between homepage links and deeper pages.
- Review anchor text distribution for anomalies.
- Verify paid placements carry correct
sponsoreddisclosure. - Check Search Console for manual actions.
- Collect unlinked brand mentions and follow up.
- Benchmark three direct competitors – within the same niche only.
- Define two or three realistic link angles for the next six months.
Pro tip: with Rank-O-Saur you can vet a prospective link source as you visit it: is the page indexable, how many outbound links does it carry, which rel attributes are set and what are the anchor texts. That covers half the checklist in section 5.
12. Frequently asked questions
How many backlinks do I need to rank?
There is no universal number. What matters is the comparison with the pages that actually rank for your target queries. In low-competition niches a page can rank with no external links; in competitive markets hundreds of referring domains are normal.
Are nofollow backlinks worthless?
No, but they work differently. They generally pass no link equity, yet they bring traffic, visibility and brand awareness. Since 2020 Google also treats nofollow as a hint rather than a strict directive.
Can bad backlinks harm my site?
In most cases no. Google devalues manipulative links automatically instead of penalising the site. Real risk exists mainly where you systematically bought or built links yourself – then a manual action can follow.
Am I allowed to buy backlinks?
Links that pass ranking signals in exchange for payment breach Google's spam policies. Paid placements are only acceptable with rel="sponsored" or rel="nofollow". On top of that, most jurisdictions require paid content to be disclosed as advertising.
Is a link from a strong domain always better?
No. Topical relevance and editorial nature outweigh raw domain strength. In practice a contextual link from a relevant specialist article on a mid-sized site beats a footer link from a strong but unrelated domain.
How long until a backlink takes effect?
Google first has to crawl and process the linking page. For frequently crawled sources that is days; for rarely crawled ones, weeks. A measurable ranking change from an individual link is rarely provable in isolation anyway.
Should I point all backlinks at the homepage?
No. Links to the matching deeper page work more directly, because the relevance signal lands where the content is. A natural profile contains links to both the homepage and deeper pages. How the strength then spreads internally is covered in the internal linking guide.
Do social media links count as backlinks?
Technically yes, practically barely: most platforms apply nofollow or ugc. Their value lies in reach and discovery – a shared post can lead to someone else placing an editorial link.
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