Backlink

A backlink is a hyperlink on one website that points to a page on another website. From the receiving site's perspective, it is an inbound link. Backlinks are the foundational unit of off-page SEO because they are what gave the original PageRank algorithm something to count.

Not all backlinks are equal. A link's value depends on at least five factors: the authority of the source page and source domain, the topical relevance between source and target, the Anchor Text used, the link's attribute (Dofollow versus Nofollow), and its placement on the source page. An editorial link inside the body of a relevant article on a strong domain is worth orders of magnitude more than a footer link in a sidebar widget on an unrelated site.

Operators distinguish between backlinks and Referring Domain counts. A single domain might link to you hundreds of times across many pages — that is one referring domain producing many backlinks. The unique-domain count is generally a better health metric than the raw backlink count, because diversity matters and a single domain's link can be added or removed in bulk.

Backlinks are evaluated by search engines as both a quantity signal (a site with thousands of relevant referring domains is more likely to be considered authoritative) and a quality filter (a site with millions of low-quality links from spam networks often gets discounted, ignored, or penalised). The shift in emphasis from quantity to quality has been continuous since the Penguin update in 2012.

Building backlinks ethically is called link earning or Link Building. Tactics span digital PR, Guest Post placements, original research, broken-link reclamation, and resource-page outreach. Tactics that violate Google's guidelines — paid link schemes, PBN (Private Blog Network) networks, automated comment spam — can lead to manual actions or algorithmic suppression.

For ongoing tracking, monitor referring-domain growth, Lost Backlink alerts on high-authority sources, and Toxic Backlink patterns. The link profile is a living asset, not a one-time deliverable.