What Are Backlinks?

Backlinks, also known as inbound links or incoming links, are hyperlinks on one website that point to a page on another website. When Site A links to Site B, Site B has earned a backlink from Site A.

Search engines like Google treat backlinks as votes of confidence. The more high-quality backlinks a page has, the more authoritative it appears, and the higher it tends to rank in search results.

Why Backlinks Matter for SEO

Backlinks remain one of the most influential ranking factors in Google's algorithm. Here is why they are so important:

Authority and Trust. Each backlink signals to search engines that another site found your content valuable enough to reference. Links from authoritative domains (like major publications, universities, or government sites) carry significantly more weight than links from low-quality or spammy websites.

Discoverability. Search engine crawlers follow links to discover new pages. A strong backlink profile helps search engines find and index your content faster.

Referral Traffic. Beyond SEO value, backlinks drive direct traffic. A well-placed link on a popular blog or resource page can send a steady stream of visitors to your site.

Competitive Advantage. In competitive niches, backlinks often determine which pages rank on the first page. Two pages with similar content quality will often be separated by the strength of their backlink profiles.

Types of Backlinks

Not all backlinks are created equal. Understanding the different types helps you build a stronger link profile.

Dofollow vs. Nofollow

Google supports three rel attribute values for qualifying links, and as of September 2019 it treats all three as hints rather than absolute directives. The documentation states that links marked with these attributes "will generally not be followed," though the linked pages may still be discovered and crawled through other means such as sitemaps.

• Dofollow links carry no qualifying attribute, so they pass full ranking signal (link equity) to the linked page. This is the default link type and the most valuable for rankings.
• Nofollow links use rel="nofollow". Google's guidance is to use this value "when other values don't apply, and you'd rather Google not associate your site with, or crawl the linked page from, your site."
• Sponsored links use rel="sponsored". Google says to "mark links that are advertisements or paid placements (commonly called paid links) with the sponsored value."
• UGC links use rel="ugc", recommended for links inside user-generated content such as comments and forum posts.

Values can be combined as a space- or comma-separated list, for example rel="ugc nofollow" or rel="sponsored nofollow", when more than one description fits a single link.

Editorial vs. Non-Editorial

• Editorial backlinks are earned naturally when someone links to your content because they find it useful. These are the most valuable type.
• Non-editorial backlinks come from directories, forums, profiles, or other self-placed links. They carry less weight but still contribute to a natural link profile.

What Makes a Backlink High Quality?

Several factors determine the value of a backlink:

How to Build Backlinks

Building backlinks requires effort, but several proven strategies exist:

1. Create linkable content. Original research, comprehensive guides, infographics, and free tools naturally attract links because they provide unique value.
2. Guest posting. Write high-quality articles for relevant blogs in your industry. Most allow at least one link back to your site.
3. Broken link building. Find broken links on other websites and suggest your content as a replacement. This provides value to the site owner while earning you a link.
4. Digital PR. Create newsworthy content, run original studies, or offer expert commentary to journalists. Media coverage generates authoritative backlinks.
5. Resource page outreach. Identify resource pages in your niche and pitch your content for inclusion.
6. Competitor analysis. Use tools like Ahrefs or SEMrush to see where competitors earn their backlinks, then target those same sources.

Common Backlink Mistakes to Avoid

• Buying or selling links for ranking purposes. Google's spam policies name this directly, including exchanging money, goods, or services for links or for posts that contain links. Google notes that such commercial links are not a violation as long as they are qualified with a rel="nofollow" or rel="sponsored" value. Sites caught publishing or acquiring unqualified paid or guest-post links can face algorithmic or manual action.
• Low-quality directories. Submitting to hundreds of irrelevant directories signals spam to search engines.
• Excessive exact-match anchors. Over-optimizing anchor text with exact keywords looks unnatural and can trigger penalties.
• Ignoring toxic links. Regularly audit your backlink profile and disavow spammy or harmful links using Google's Disavow Tool.

How to Monitor Your Backlinks

Use these tools to track your backlink profile:

• Google Search Console provides a free list of linking sites and pages.
• Ahrefs offers the most comprehensive backlink database with detailed metrics.
• SEMrush includes backlink analytics and a toxic link audit tool.
• Moz Link Explorer shows domain authority and linking domains.

Regular monitoring helps you identify new link opportunities, spot toxic links early, and measure the impact of your link building efforts.

In Practice

Say a SaaS review blog publishes a roundup that links out to three vendors. One is a normal editorial mention, one is a paid placement the vendor sponsored, and one sits inside a reader comment. Each link should be qualified differently so Google can read the relationship correctly.

<!-- Editorial mention earned on merit: pass full ranking signal -->
<a href="https://example.com/best-tool">our top pick this year</a>

<!-- Paid placement the vendor sponsored -->
<a href="https://vendor.com/landing" rel="sponsored">Vendor X pricing</a>

<!-- Link a reader dropped in the comments -->
<a href="https://reader-site.com/post" rel="ugc nofollow">a reader's writeup</a>

For the site receiving these links, the editorial one is the prize because it passes ranking signal and was given freely. The sponsored and UGC links still appear in a healthy, natural link profile, they simply do not pass the same ranking credit. Mislabeling the paid link as a plain dofollow link is exactly the pattern Google's link spam systems look for, so the correct attribute protects both the linking site and the linked site.

Related Terms

• What Is Link Building? covers the strategies used to earn the links described here.
• What Is a Nofollow Link? explains the attribute in depth, including how Google now treats it as a hint.
• What Is a Dofollow Link? details the default link type that passes ranking signal.
• What Is Anchor Text? describes the clickable text that gives a backlink its topical context.
• What Is Link Equity? breaks down the ranking value a backlink can transfer.

Sources

• Qualify Outbound Links for SEO - Google Search Central (checked 2026-05-30)
• Spam Policies for Google Web Search - Google Search Central (checked 2026-05-30)
• Evolving "nofollow", new ways to identify the nature of links - Google Search Central Blog (checked 2026-05-30)

Key Takeaways

Backlinks are foundational to SEO success. Focus on earning high-quality, relevant links through valuable content and legitimate outreach. Avoid shortcuts like buying links or participating in link schemes. A strong, natural backlink profile built over time will consistently improve your search rankings and drive organic traffic.