A backlink (also called an inbound link or external link) is a hyperlink on one website that points to a page on a different website. When Website A links to Website B, Website B has received a backlink from Website A.
Backlinks are one of Google's most important ranking signals - arguably the most important. They act like votes of confidence from one site to another, signalling to search engines that the linked content is credible, useful, and worth ranking.
Why Are Backlinks So Important?
Google's original PageRank algorithm was built around the concept of links as votes. The more authoritative links pointing to a page, the higher it should rank. While the algorithm has evolved significantly, links remain a core ranking factor over two decades later.
Studies consistently show a strong correlation between the number of quality backlinks and high search rankings. Pages with more backlinks from authoritative domains almost always outrank pages with fewer or lower-quality links.
Dofollow vs. Nofollow Backlinks
Not all backlinks pass the same value:
- Dofollow - The default link type. Passes "link equity" (sometimes called "link juice") to the target page and directly influences rankings.
- Nofollow (rel="nofollow") - Tells search engines not to follow the link or pass authority. Common in blog comments, forum posts, and sponsored content.
- Sponsored (rel="sponsored") - Used for paid or affiliate links. Google uses this to identify commercial relationships.
- UGC (rel="ugc") - Used for user-generated content like comments and forum posts.
What Makes a Backlink Valuable?
Not all backlinks are equal. A single link from a top newspaper can be worth more than hundreds of links from low-quality directories. Key factors include:
- Domain Authority - Links from high-authority, trusted sites carry more weight.
- Relevance - A link from a site in your industry is more valuable than one from an unrelated niche.
- Placement - Links in the body of editorial content are worth more than those in footers or sidebars.
- Anchor Text - Descriptive anchor text helps Google understand the context of the link.
- Uniqueness - The fewer links a page has given out, the more valuable each individual link is.
How to Build Backlinks
Earning quality backlinks requires creating content worth linking to and then promoting it strategically. Common approaches include:
- Creating original research, data, or infographics
- Guest posting on relevant industry blogs
- Broken link building (finding dead links and offering your content as a replacement)
- Digital PR and media outreach
- Resource page link building
Key Takeaways
- A backlink is a link from another website pointing to yours.
- Quality matters far more than quantity.
- Dofollow links pass authority; nofollow links generally do not.
- Earning links from relevant, authoritative sites is the foundation of off-page SEO.