In linking 2 pages with Next.js I mentioned how the Link Next.js component can be used to create links between 2 pages, and when you use it, Next.js transparently handles frontend routing for us, so when a user clicks a link, frontend takes care of showing the new page without triggering a new client/server request and response cycle, as it normally happens with web pages.

There’s another thing that Next.js does for you when you use Link.

As soon as an element wrapped within <Link> appears in the viewport (which means it’s visible to the website user), Next.js prefetches the URL it points to, as long as it’s a local link (on your website), making the application super fast to the viewer.

This behavior is only being triggered in production mode (we’ll talk about this in-depth later), which means you have to stop the application if you are running it with npm run dev, compile your production bundle with npm run build and run it with npm run start instead.

Using the Network inspector in the DevTools you’ll notice that any links above the fold, at page load, start the prefetching as soon as the load event has been fired on your page (triggered when the page is fully loaded, and happens after the DOMContentLoaded event).

Any other Link tag not in the viewport will be prefetched when the user scrolls and it

Prefetching is automatic on high speed connections (Wifi and 3g+ connections, unless the browser sends the Save-Data HTTP Header.

You can opt out from prefetching individual Link instances by setting the prefetch prop to false:

<Link href="/a-link" prefetch={false}>
  <a>A link</a>
</Link>