The fetchpriority HTML attribute is a Priority Hints mechanism that allows developers to signal the relative importance of a resource to the browser’s fetch priority queue, overriding the default heuristics. It accepts three values: high, low, and auto (the default). It can be applied to <img>, <link>, <script>, and <iframe> elements. The most impactful use case identified by Google is setting fetchpriority="high" on the LCP image, which tells the browser to fetch it at the same high priority as render-blocking resources rather than waiting for it to be discovered during layout. Conversely, setting fetchpriority="low" on below-the-fold images or non-critical scripts reduces their competition for bandwidth during the critical loading phase. The attribute was standardised and shipped in Chrome 101 in 2022, with Safari and Firefox adding support in 2023. Lighthouse’s “Prioritise LCP image” audit specifically recommends adding fetchpriority="high" to the LCP element as a zero-cost optimisation for improving Core Web Vitals.