A backlink is a hyperlink on one website that points to a page on another website. When Site A links to Site B, Site B has received a backlink from Site A. Also called inbound links, incoming links, or external links (from the receiving site's perspective).
Simple Definition
Think of a backlink as a citation or reference. When someone links to your website, they're essentially saying "this page has something worth looking at." Search engines interpret backlinks as votes of confidence.
Example: If a news article about gardening links to your plant care guide, you've earned a backlink from that news site.
Why Backlinks Matter
Search Engine Ranking Factor
Backlinks have been a core ranking factor since Google's founding. The original PageRank algorithm was built on the idea that pages with more quality links deserve higher rankings.
How search engines use backlinks:
- Measure authority and trust
- Understand topic relationships
- Discover new content
- Validate content quality
Referral Traffic
Beyond SEO, backlinks drive direct visitors. When someone clicks a link to your site, that's referral traffic—often high-quality since it comes with context.
Discovery and Indexing
Search engine crawlers follow links to discover new pages. Backlinks help ensure your content gets found and indexed.
Backlink Anatomy
Every backlink has key components:
Source Page
The page containing the link (where the link comes from).
Target Page
The page being linked to (where the link points).
Anchor Text
The clickable text of the link. Provides context about the target page.
Link Attributes
HTML attributes that modify link behaviour:
rel="nofollow"- Suggests not passing ranking valuerel="sponsored"- Marks paid linksrel="ugc"- Marks user-generated content
Link Context
The surrounding content and the linking page's topic affect how search engines interpret the link's relevance.
Types of Backlinks
By Link Attribute
Do-follow links: Standard links that pass ranking signals. Most valuable for SEO.
No-follow links: Links with rel="nofollow" attribute. Originally didn't pass value; Google now treats as a "hint."
Sponsored links: Marked as paid/advertisement with rel="sponsored".
UGC links: Links in user-generated content marked with rel="ugc".
By Acquisition Method
Natural/Editorial links: Given organically because someone found your content valuable.
Outreach links: Earned through direct contact—guest posts, resource requests, etc.
Self-created links: Placed by you in forums, comments, directories. Generally lowest value.
By Placement
Contextual links: Within body content, surrounded by relevant text. Most valuable.
Navigation links: In menus or site navigation.
Footer links: In page footers. Often site-wide.
Sidebar links: In page sidebars or widgets.
Comment links: In blog comments. Usually nofollow.
What Makes a Good Backlink?
Quality Indicators
Relevance: Link comes from a topically related site or page.
Authority: Linking site has strong domain authority and trust.
Placement: Link is contextual, within main content.
Editorial: Link was given naturally, not paid for or exchanged.
Traffic: Linking site has real visitors, not just metrics.
Warning Signs
Irrelevance: Link from completely unrelated site.
Spam signals: Linking site is low-quality or spammy.
Manipulation: Link was clearly paid for or part of a scheme.
Over-optimised anchor text: Exact-match anchor text at scale.
Backlink vs Related Terms
Backlink vs External Link
Same link, different perspective:
- Backlink: Viewed from the receiving site's perspective
- External link: Viewed from the linking site's perspective
Backlink vs Internal Link
Different link types:
- Backlink: From another domain to yours
- Internal link: From one page on your domain to another
Backlink vs Referring Domain
Different metrics:
- Backlink: An individual link
- Referring domain: A unique domain that links to you (may have multiple backlinks)
How to Get Backlinks
Content-Driven Methods
- Create comprehensive, valuable content
- Publish original research with data
- Build useful tools or resources
- Develop visual content (infographics, charts)
Outreach Methods
- Guest posting on relevant sites
- Resource page link building
- Broken link replacement
- Digital PR and media coverage
Relationship Methods
- Build industry connections
- Participate in communities
- Collaborate with complementary businesses
Full guide: How to Start Link Building →
Measuring Backlinks
Key Metrics
Total backlinks: Raw count of all links pointing to your site.
Referring domains: Unique domains linking to you (often more meaningful than total links).
Do-follow ratio: Percentage of links passing ranking value.
Anchor text distribution: Mix of anchor text types.
Domain authority of sources: Quality level of linking sites.
Tools for Analysis
- Ahrefs
- Semrush
- Moz Link Explorer
- Google Search Console (limited but free)
- Majestic (explore alternatives to Majestic if you need different features)
On a budget? Check out our roundup of free tools for checking backlinks to get started without a paid subscription.
Common Questions
How many backlinks do I need?
There's no universal number. Focus on quality over quantity. The "right" number depends on your competitive landscape—analyse competitors ranking for your target keywords.
Do all backlinks help?
No. Low-quality, spammy, or irrelevant backlinks can potentially harm your rankings. A few quality backlinks often beat many poor ones.
How long until backlinks impact rankings?
Varies significantly—days to months. New links need to be discovered and processed. Impact depends on the link's quality and your site's existing authority.
Should I disavow bad backlinks?
Only if you have clear evidence of spammy links and potential penalty risk. Most sites don't need to use disavow.
Summary
A backlink is a link from another website to yours. Backlinks:
- Act as votes of confidence
- Influence search rankings
- Drive referral traffic
- Help with content discovery
Focus on earning quality backlinks from relevant, authoritative sources through valuable content and legitimate outreach.
Free Tools
- Free Backlink Checker - Check any website's backlinks instantly
- Backlink Audit Checklist - Step-by-step audit guide