Lazy Loading
A technique that defers loading of off-screen images and content until the user scrolls near them, reducing initial page load time.
Lazy loading improves performance by loading only the content visible in the viewport on initial page load. Images below the fold remain as lightweight placeholders until the user scrolls toward them, triggering the actual image download. Native lazy loading via the HTML loading='lazy' attribute is supported by all modern browsers and requires no JavaScript. The Intersection Observer API provides more control for custom implementations. For above-the-fold hero images, lazy loading should be disabled — these images need immediate loading for optimal Largest Contentful Paint. Aggressive lazy loading that delays visible content harms perceived performance. The balance is immediate loading for visible content and deferred loading for everything else.