Backlink

Long definition

A backlink is any <a href> originating outside your domain that resolves to a URL on your domain. Internal links don't count. The reason backlinks matter at all traces back to Brin and Page's 1998 PageRank paper: a link is treated as an editorial vote, and votes from authoritative pages carry more weight than votes from random ones.

Modern Google has layered intent classification on top of raw PageRank — the rel attribute now changes the calculus:

• rel absent (colloquially "dofollow") — default. Passes link equity. Anchor text is read as a relevance signal.
• rel="nofollow" — was a directive (2005-2019), now a hint. Google may use the anchor and target as context but typically doesn't pass equity.
• rel="sponsored" — required since September 2019 for paid/affiliate placements. Treated similarly to nofollow but signals intent.
• rel="ugc" — user-generated content (forums, comments, reviews). Hint, treated like nofollow.

A useful framing: a backlink's value is anchor text + linking page authority + topical relevance + trust of the source, divided by total outbound links on the source page. One link from a Wikipedia citation in your topic is worth more than 1,000 from a comment-spam blog.

Backlinks remain heavily weighted because they are hard to fake at scale. Penguin 4.0 (2016) made link spam algorithmically devalued rather than penalized — bad links are usually ignored, not punished. That's why disavow files matter less today than they did a decade ago.

Common misconceptions

• "More backlinks always help." Quality and topical relevance dominate. 10 links from cited industry sources beat 10,000 from PBN footprints. Google's link evaluation has been pattern-matching footprints since 2012.
• "All nofollow links are wasted." They contribute referral traffic, brand exposure, and indirect authority signals. Google may still use the anchor for context. Wikipedia links are nofollowed and still highly valuable.
• "You can't rank without backlinks." For low-competition long-tail queries, on-page relevance and freshness can suffice. For competitive head terms, backlink authority is usually load-bearing.
• "A backlink from a high-DR site is automatically valuable." DR is Ahrefs' proprietary score. The link's actual value depends on the linking page's authority and topical fit, not the domain's headline number.