Backlink
Also known as: Inbound link
A backlink is a link from another website to yours, historically one of the strongest signals of a site's standing.
In full
A backlink is a hyperlink on another website pointing to yours. Search engines have treated links as votes of confidence since their earliest ranking systems, on the reasoning that people link to things they find useful. Not all backlinks carry equal weight: a link from a widely trusted, topically relevant site is worth vastly more than one from a low-quality directory, and links marked with the nofollow, sponsored, or ugc attributes are treated differently. Buying links breaches Google's spam policies and risks a manual action against the site.
Why it matters
For a new domain, the absence of backlinks is usually the binding constraint on ranking rather than anything on the site itself. Earning them is slow, which is why it is the part most often skipped.
A common misconception
That backlinks are the dominant factor in AI visibility. Research correlating AI brand visibility with various factors has found unlinked brand mentions and presence on community platforms correlate considerably more strongly than raw backlink counts.