For well known performance reasons, client side caching of web resources like stylesheets, images and scripts is important. This becomes pretty important for those who are creating mobile/tablet Visualforce pages for Salesforce 1. Luckily HTML5  Application Cache is well supported on Visualforce + Salesforce 1 stack, please refer this official document for more details.

Read More: https://www.concret.io/blog//2014/09/auto-updating-html5-cache-manifest-for-salesforce1-visualforce-mobile-pages.html