What Are Backlinks? SEO Definition, Types & How to Earn Them

A backlink is an inbound hyperlink from one website to another. In SEO parlance, they are also called inbound links, external links, or simply "links." Google's original PageRank algorithm treated links as votes of confidence — if reputable sites link to your page, that page is probably worth surfacing in search results. Links remain one of the strongest off-page ranking signals more than two decades later, even as Google's evaluation of link quality has grown far more sophisticated.

Dofollow vs. Nofollow

By default, most links pass PageRank (often called "link equity" or "link juice"). A rel="nofollow" attribute tells Google not to pass ranking credit through that link. Sponsored content uses rel="sponsored"; user-generated links often carry rel="ugc". Since 2019, Google treats all three as hints rather than hard directives — it may still choose to count a nofollow link as a signal in some cases.

Nofollow links from major publications still drive referral traffic, brand visibility, and indirect SEO benefits when they lead to further coverage and organic links. Do not dismiss them entirely.

What Makes a Backlink Valuable

Relevance matters more than raw authority. A link from a DR 30 site in your exact industry carries more ranking weight than a link from a DR 70 general news site on an unrelated topic. Editorial placement within body content outperforms footer or sidebar links. Unique referring domains count more than hundreds of links from the same domain. Anchor text that describes the linked page naturally helps Google understand context — but over-optimized exact-match anchor text across many links triggers spam filters.

Link Types That Usually Fail

Paid link schemes, private blog networks, mass directory submissions, and automated guest post farms tend to produce temporary gains followed by manual actions or algorithmic devaluation. Google's spam policies explicitly penalize link schemes designed to manipulate rankings. If a link offer sounds too easy — "DR 60+ guest posts for $50" — it probably is.

Earning links through original research, useful tools, expert commentary, and genuine relationships scales slower but compounds. That is the work covered in depth in our link building guide, which walks through digital PR, broken link building, and outreach that actually gets responses.