Facebook recently announced its goal to improve user experience by helping businesses be the best mobile advertisers they can be. In a similar effort, they are working towards developing new tools and insights to shorten mobile site load time. Pre-fetching, as Facebook termed it, is the latter's approach towards downloading mobile content in advance. Therefore, if you've created a mobile ad that includes a link to your mobile website, a portion of the content is already linked or prefetched with Facebook. This way, the content will appear more quickly. This will especially eliminate the issue faced by those with slow or poor network connections.
This will help the companies and publishers in a huge way as well. Prefetching will quite naturally increase traffic for them.
Furthermore, in order to distinguish between prefetched clicks and normal requests or clicks, Facebook has adopted the standard industry practice of including a header 'X-Purpose: preview' in these requests for the publishers and third-party companies to understand the same.
