Preloading
Preloading is a web performance optimization technique that involves fetching critical resources (such as scripts, stylesheets, fonts, or images) early in the page load process, before they are needed, to reduce latency and improve user experience. It uses browser hints like the <link rel='preload'> HTML tag or HTTP headers to inform the browser about resources that will be required soon, allowing them to be downloaded with higher priority. This helps prevent render-blocking delays and ensures smoother page interactions.
Developers should use preloading when optimizing web applications for speed, particularly for resources that are essential for above-the-fold content or critical user interactions, such as custom fonts, JavaScript bundles for initial rendering, or large images. It is especially valuable in single-page applications (SPAs) and progressive web apps (PWAs) to reduce time-to-interactive and first-contentful-paint metrics, leading to better SEO rankings and user retention.