Link decay refers to the gradual loss of inbound links over time as pages that once linked to a site are deleted, redesigned, or allowed to expire. Research published by Ahrefs and others consistently shows that a meaningful percentage of backlinks — often estimated at five to eight percent annually — disappear each year without any action by the recipient site. Decay accelerates when a linking domain is sold, taken offline, or migrated without proper redirects. The practical consequence is that a site’s link profile shrinks in both quantity and diversity unless new links are actively acquired to offset the losses. SEO practitioners typically monitor decay through regular backlink audits, set up alerts for lost links, and use link reclamation outreach to recover high-value links before the ranking benefit fully dissipates.