Backlinks are one of the most important signals search engines and AI systems use to decide which sites deserve visibility.

This guide breaks down what backlinks are, why they matter across both organic and AI search, the factors that affect their value, and proven ways to build them.

Backlinks are a credibility record, not just a ranking signal

Every time another reputable website links to yours, it's casting a vote of confidence in your content.

Over time, those votes accumulate into something more significant than a ranking factor. They form a credibility record that both search engines and AI systems draw on when deciding what to surface.

Search engines like Google have used this record for decades. But AI search tools (including AI Overviews, ChatGPT, and Perplexity) are now drawing on it, too. 

When AI search systems generate responses and decide which sources to cite, they're leaning heavily on the same signals of authority and trustworthiness that search engines have always valued. That means sites with strong backlink profiles are ranking well on Google and being cited in AI-generated answers.

Think of your backlink profile as one record with two evaluators. 

Your backlink profile doesn't change depending on who's evaluating it. A link from a respected industry publication carries weight, whether it's a search engine crawler following it or an AI system assessing your site's credibility. Both are asking the same underlying question: “Is this a source worth sending people to?”

If backlinks were purely a ranking mechanism, their value would fluctuate every time an algorithm update changed how they're weighted. But as a credibility record, they're more durable (and more broadly useful) than that.

What are backlinks?

Backlinks are links from other websites pointing to yours that signal trust and authority to improve your visibility in search engine results and AI-generated answers.

Plus, backlinks can also drive referral traffic directly from those linking sites to yours.

From the perspective of the site linking out, these are called external links, outbound links, or outgoing links. But when other sites link to your website, they become your backlinks.

You can acquire backlinks naturally when other sites discover and link to your content. Or you can proactively build them through outreach and by cultivating relationships.

To quickly see your site's backlinks (or any competitor's backlinks), use our free Backlink Checker.

Types of backlinks

Not all backlinks are the same. Here are the main types and what each signals to your credibility record:

• Editorial backlinks: Links that are earned naturally when a site links to your content as a trusted source. These provide the strongest credibility signal.
• Guest post backlinks: Links that are placed within content you've written for another site. These signal relevance and expertise when the host site is topically aligned with your site.
• Business profile and directory backlinks: Links from listings, associations, or partner pages. These signal legitimacy and local or industry presence.
• UGC and sponsored backlinks: Links in user-generated content (e.g., forums and comments) or paid placements, typically marked nofollow. These were historically treated as lower-credibility signals, though Google has acknowledged that nofollow is just a hint, so these can still contribute to visibility.
• Social backlinks: Links from social media platforms. While they might not carry much direct SEO value, they drive traffic and put your content in front of audiences who may link to it from their own sites.

For a deeper breakdown, see our guide to the different types of backlinks.

Why backlinks matter for search engine and AI visibility

Backlinks matter in SEO and AI SEO because they signal that your content is reputable and that your website is authoritative.

The backlinks you acquire are a powerful signal that search engines and AI systems use to evaluate whether a site deserves visibility, but they work slightly differently across each.

In organic search, Google uses backlinks as a core input to its PageRank algorithm. PageRank can be thought of as a measure of page authority. And pages pass authority (also known as link equity) to each other through links.

The higher a page’s PageRank, the more equity it can pass to the pages it links to. 

Pages with strong backlink profiles pass more equity to the pages they link to. That boosts authority across your site without diminishing the authority of those already reputable pages.

You can see the impact of strong backlink profiles on competitive queries. For instance, the top-ranking pages for "iphone reviews" have hundreds of backlinks: 

And the corresponding domains have millions of backlinks:

In AI search, the relationship between backlinks and performance is equally significant. A Semrush study of 1,000 domains found that high-quality backlinks meaningfully improve AI visibility. 

And considering Google's AI Overviews and AI Mode are built on top of existing search infrastructure, backlinks likely play a large role in whether your content gets surfaced in Google’s AI search experiences.

Just be aware that Google's link spam policies exist to discourage manipulative link building. Violating them risks a Google penalty that can hurt your visibility across both organic search and AI experiences.

What affects the value of a backlink in SEO?

Some backlinks are more beneficial for SEO than others, some have the potential to harm your visibility, and some probably have no impact. 

Let’s explore the main factors that affect the value of a backlink in SEO:

Follow status

When a backlink has a nofollow attribute indicating the publisher doesn’t want the link to be seen as an endorsement, the link can be less valuable for improving search visibility. 

Publishers can suggest that search systems don’t follow a link by adding one of these attributes to the link’s HTML:

• rel=“nofollow”: The linking site doesn’t want to endorse the target site
• rel=“sponsored”: The target site paid for the link to be placed on the linking site
• rel=“ugc”: The link appears within user-generated content (like forum comments)

Adding one of these attributes creates a nofollow link. Like this:

<a href="https://example.com/" rel="sponsored">Click here</a>

“Follow” links (sometimes called “dofollow” links) don’t contain any of the above attributes. Google is more likely to follow these, though there's no guarantee those links will positively affect your rankings. Google has also said that even nofollow links can serve as hints for ranking purposes. 

And our study on 1,000 domains found that nofollow links have nearly the same impact on AI visibility as follow links. This supports the idea that AI systems read your backlink profile as a whole. The holistic record matters more than any single attribute on individual links.

To check whether your backlinks are marked as nofollow, use Semrush’s Backlinks tool. 

If you find a link that’s marked nofollow, consider reaching out to the relevant contact and asking them to change it to a follow link. 

Domain and page authority

The more authoritative the domain and page linking to your website, the more valuable that backlink can be.

For instance, a link from the World Health Organization carries more weight than one from a small, unknown health blog for search engines and AI systems alike. 

While Google and AI tools don't publish authority metrics, Semrush's Authority Score (AS) offers a useful approximation. 

AS measures domain and page authoritativeness based on:

• Link power: The quality and quantity of backlinks
• Organic traffic: Estimated monthly unpaid visits from search engines
• Natural profile: How natural (rather than spammy) the backlink profile appears

It's also worth targeting sites that consistently publish well-researched, accurate, and helpful content. These sites are more likely to be perceived as authoritative based on engagement signals and brand mentions.

Topical relevance

Backlinks from websites and content that are relevant to yours carry more weight because they appear more natural to search engines and more trustworthy to AI systems.

Healthline earning backlinks from the Centers for Disease Control and Prevention (CDC), for example, is more valuable than Healthline earning links from a similarly authoritative sports site.

Plus, visitors who arrive via topically relevant backlinks are more likely to engage with your content and convert.

Link placement and context

Where a link appears on a page and how likely it is to be clicked may affect how much value it passes. 

Google's reasonable surfer model patent suggests links are weighted by click likelihood, factoring in:

• Placement: Links high in the main content are more likely to be clicked than footer links, for example
• Content quality: Higher-quality content and context make a click more likely
• Link density: Fewer links on a page means more attention and value per link

Just bear in mind that we can’t say for certain whether Google actually uses this model in its algorithms. 

Anchor text

Anchor text is the clickable text a link is attached to, and it helps search engines understand what the linked page is about.

Some marketers try to build links with keyword-rich anchor text like "buy men's wedding shoes” and “wedding shoes for men online" to manipulate rankings. But unnatural anchor text is a form of link spam that can trigger a Google penalty.

Instead, use descriptive, natural-sounding anchor text. And avoid building large numbers of links with identical anchor text.

Link schemes

Link schemes are attempts to manipulate rankings and SEO performance through unhelpful or spammy backlinks. 

Google identifies and ignores most link schemes. However, participating in link schemes at scale can lead to a penalty.

Practices to avoid:

• Paying for follow links
• Participating in link exchanges (i.e., "link to me and I'll link to you")
• Using automated link building programs
• Getting links from low-quality directory sites
• Adding unnatural links in forum comments
• Creating content purely to generate backlinks

If you've engaged in any of these practices, use Semrush's Backlink Audit tool to identify potentially toxic backlinks and remove them if necessary. 

From the "Audit" report, review flagged links and move harmful ones to the "Remove" tab. From there, you can email site owners directly to request removal.

As a last resort, disavow toxic links (i.e., formally ask Google to ignore them). Only do this if you have a large volume of harmful links you can't remove and are at risk of (or have already received) a Google penalty. Disavowing incorrectly can hurt your site’s search visibility.

7 ways to build valuable backlinks for SEO

Here are seven proven link building tactics to try:

1. Create useful resources

Create useful resources that are hard for others to replicate or improve upon, so publishers have a good reason to cite your website in their content.

For example, Healthline has an in-depth article about how much water you should drink. It’s cited as a source in many related articles, like this one from HuffPost:

It’s crucial that the resources you create are highly relevant to your brand because:

• It makes your content more trustworthy and more likely to get linked to
• It means you’re more likely to attract links from topically relevant sites
• The content is more likely to generate other business benefits (like conversions from referral traffic)

Original data, proprietary frameworks, and comprehensive guides are also among the types of assets AI systems most frequently cite in their generated answers. So, the same qualities that earn editorial backlinks tend to improve AI visibility.

If you need inspiration, see which of your competitors’ pages attract the most backlinks by analyzing their domains in the Backlinks tool and going to the “Indexed Pages” report.

High-quality content like this can attract backlinks naturally. But you can also use outreach tactics to build links.

2. Try broken link building

Broken link building is the process of finding backlinks that don’t work (e.g., because the target page was deleted) and suggesting a relevant backlink to your website as a replacement.

Broken link building works well because publishers don’t want broken links on their sites. And you’re offering them an easy solution that will improve their user experience.

To find broken links, you can suggest alternatives to, look for links that were supposed to point to your site in the first place. Just go to the “Indexed Pages” report for your domain in the Backlinks tool and apply the “Broken Pages” filter.

If you have a good replacement for any broken page you see here, click the corresponding number in the “Backlinks” column. 

Then, decide which broken backlinks are worth trying to recover (if any) based on the authority of the page, the context of the link, etc.

Finally, email the relevant contact(s) to let them know about your broken backlink and your suggested replacement. Here’s an email template you can use:

Subject line: Resource suggestion for [Page Title]

Hi [Name],

I was reading your article on [topic/page title] and noticed that the link to [describe the resource briefly] appears to be broken.

Here's the specific link: [broken URL]

I recently published a similar resource that covers [brief description of your content]. If you think it would be helpful for your readers, here it is: [your URL]

Either way, I wanted to give you a heads up about the broken link.

Best,[Your name]

3. Answer relevant media requests

Finding and responding to relevant media requests can be an effective way to build website backlinks because creators often credit their contributors with a link.

You can find media requests to respond to on websites like Help a Reporter Out (HARO), Qwoted, and Featured.

Generally, you need to follow these steps when you want to use a platform to respond to media requests:

1. Sign up to your chosen platform(s) and create a profile
2. Opt in to alerts about relevant requests and monitor your email inbox
3. Respond to relevant requests as quickly and helpfully as possible 

Responding to media requests requires time and patience, as you are essentially competing with other sources. To increase your success, lead with a specific, quotable insight. Journalists are on a deadline and need copy they can use immediately.

Check out our guide to HARO link building to learn how to use this tactic effectively.

4. Run digital PR campaigns

Digital PR is the practice of creating newsworthy content and distributing it to journalists and publishers to earn coverage and backlinks at scale.

Unlike reactive media requests, most PR campaigns are proactive. You create the story, then pitch it.

For example, in 2022, the marketing agency Yard published a report on which celebrities contributed the most to CO2 emissions from their private jet use.

Since then, Yard’s study has earned roughly 2,800 links from over 1,100 different websites and publications.

When your digital PR campaign is done right, your referring domains should skew more toward links from mass media, newspapers, and publishers.

Effective digital PR assets tend to be:

• Original data: Surveys, studies, or proprietary datasets journalists can't get elsewhere
• Timely angles: Content tied to news cycles, seasonal trends, or cultural moments
• Visually compelling: Infographics or interactive content that's easy for publishers to embed

You’ll need to research what stories different publications are focusing on and align your angle to match. 

You can also use services like Pitchbox and Muckrack to widely distribute your content and allow journalists to organically pick up your story to share.

The goal is to earn some links and brand placements in major publications because they carry outsized weight for your search and AI visibility. A single high-authority citation can improve your chances of appearing in AI-generated answers more than dozens of low-authority links.

5. Guest post on relevant sites

Guest posting content on other sites in your niche helps you earn topically relevant backlinks and build a consistent presence across credible publications that AI systems use as a trust signal.

Focus on sites that publish well-researched content in your space, have a real audience, and where a link back to your site would make contextual sense. 

Avoid sites that exist purely to host guest posts. These carry minimal credibility and can look manipulative to search engines.

Before pitching, check the target site's Authority Score and backlink profile in the Backlinks tool. If their profile looks thin or spammy, move on.

When pitching, lead with a specific article idea rather than a general offer to write. Editors respond better to a concrete, relevant angle they can say yes or no to.

6. Replicate your competitors’ backlinks

Replicating competitor backlinks can be a highly effective tactic because it means using methods that have already worked.

To get started, add your domain and up to four rival domains to the Backlink Gap tool.

You’ll see the “Best” link building prospects by default. These are domains that link to all analyzed competitors but not to you.

Click the arrows in the corresponding rows and columns to learn more about your competitors’ backlinks. And determine if those links are possible (and worthwhile) to replicate.

For example, if your competitor has a backlink because their CEO gave an interview to the site, you might want to contact the publisher to see if they’re interested in interviewing your CEO, too. 

7. Capitalize on business relationships

Use your existing business relationships to try to get backlinks placed on your partners’ websites.

For example, you can get backlinks through existing relationships by:

• Supplying case studies to service providers
• Providing testimonials to freelancers
• Getting featured as a preferred vendor on distributors' websites
• Announcing joint projects on partners' blogs
• Getting listed on trade association websites

To get started, list all the website owners that your business has an affiliation with. Then, explore their sites to look for link building opportunities.

Once you have an idea, consider who at your business has the strongest relationship with the partner. Ask them to review the idea and propose it to their contact.

Track your link building work and brand credibility

Building backlinks is an ongoing process, and monitoring your credibility record over time is just as important as the outreach itself.

Semrush's Brand Monitoring app lets you track both backlinks and unlinked mentions in one place. 

Unlinked mentions are worth paying attention to because search engines and AI systems pick up on brand signals across the web. A consistent mention pattern from credible sources reinforces your authority even without a link, and they're easy outreach targets to convert into one.

Try the Brand Monitoring app today.