Resource hints are a family of HTML <link> relationship types that allow developers to provide the browser with advance information about resources or origins it will need, enabling the browser to begin connection or fetch operations ahead of when those resources would normally be discovered. The four core resource hints are dns-prefetch (resolve the DNS for an origin), preconnect (establish a full connection including TLS), prefetch (low-priority fetch of a resource for a future navigation), and preload (high-priority fetch of a resource needed for the current page). A fifth, modulepreload, is specific to JavaScript ES modules. The specification is maintained by the W3C. Resource hints are purely advisory — the browser may ignore them based on network conditions, cache state, or device constraints. Used correctly, they can significantly reduce the latency of critical resources and improve Core Web Vitals, particularly Largest Contentful Paint. Overuse or incorrect application can waste bandwidth and compete with genuinely critical fetches, so each hint should be applied based on measured impact.