A backlink is any link from one website pointing to another, and it remains one of the most influential ranking signals in SEO, functioning as a kind of vote of confidence: a site linking to another is implicitly telling both readers and search engines that the destination is worth pointing people toward.
Not all backlinks carry equal weight. A link from an established, topically relevant, genuinely authoritative site passes far more value than one from a low-quality or unrelated source, and quality and relevance generally matter more than raw quantity. A profile built on a small number of excellent, relevant links tends to outperform one padded with hundreds of weak or spammy ones, and the latter can actively hurt a site if it reads as manipulative rather than earned. Since backlinks aren't entirely within a site's own control, competitors and bad actors can point spam links at a target deliberately, regular backlink audits, using free or paid tools to review what's actually linking in, and disavowing genuinely harmful links through Search Console are standard defensive practice rather than a one-time setup task.
