Pre-rendering, or prerendering, is a web browser feature that can speed up your web surfing experience. When you view a web page, some content from another page or site might be prerendered in the background, in anticipation that you will go there next. If you do, the new page loads very quickly because some of its elements were rendered ahead of time.
For example, the first web page on the list of Google's search results is always prerendered if the browser supports it. Google assumes the top result is the most likely result to be clicked, so it asks the browser to begin rendering this page as if the user had already requested it.
<link rel="prerender" href="url">