Prerendering is an optimization technique in which the browser renders an entire page (parsing HTML, applying CSS, executing JavaScript) in the background before the user actually navigates to it. When the link is clicked, the already-rendered page appears instantly, creating a perceived zero-second page transition.
Chrome supports prerendering through the Speculation Rules API. By adding a <script type="speculationrules"> block to the HTML and specifying URL patterns, developers can instruct Chrome to prerender pages the user is likely to visit next.
Prerendering can dramatically improve the redirect experience of shortened URLs. Normally, clicking a short link triggers DNS resolution, a TCP connection, a redirect response, another DNS resolution for the destination, and finally the page load. With prerendering, all of these steps complete in advance, so the page appears the moment the user clicks.
The trade-off is resource consumption. Prerendering downloads and executes the full page in the background, consuming bandwidth and device memory. On mobile connections this can be costly, so prerendering should target only high-confidence links.
Lighter alternatives exist on a spectrum: dns-prefetch (DNS resolution only), preconnect (DNS + TCP + TLS), and prefetch (resource download without rendering). Choose the level that balances resource cost against perceived speed gain. You can find related books on Amazon.