Backlink

A backlink is an inbound link from another site to yours. From your perspective, every external page that links to one of your URLs is a backlink. From the linking site's perspective, that same link is an outbound link.

Backlinks have been a core Google ranking factor since PageRank was published in 1998. The intuition: a link from one site to another is an editorial vote of confidence, similar to a citation in an academic paper. Google measures both the quantity of backlinks (how many sites link to you) and the quality (the authority of the linking sites, the relevance of their content, the trustworthiness of their domains).

Not all backlinks are equal. A backlink from Wikipedia, The New York Times, or a high-DA domain in your niche can be worth more than a thousand backlinks from low-quality directories or comment-spam sites. Toxic backlinks (paid link networks, hacked-site link injections) can actively hurt your rankings — these are what Google's Disavow Tool is designed to neutralize.

The 2026 link-building tactics that still work: publishing data studies and original research that journalists cite, building free tools that other tool collectors link to, creating in-depth content (the 'skyscraper' approach), guest posting on real industry publications, getting listed in 'best of' roundups, and submitting to relevant industry directories. Tactics that no longer work: PBNs (private blog networks), comment-spam, link exchanges, low-quality directories.

Measurement: Ahrefs / SEMrush / Moz to track your backlink profile, Google Search Console's Links report for Google's own view of inbound links to your site. Track referring domains (unique linking sites) more than total backlinks — 10 referring domains from real publications is worth far more than 1,000 backlinks from a single low-quality site.