In this chapter, we’ve taken a (necessarily) brief look at packaging websites to act as apps for release through app marketplaces. I discussed the difference between hosted and packaged apps, the manifest files required for submitting to two web-based marketplaces, and the W3C’s own manifest standard. I also covered hybrid apps, which use web technologies in a native wrapper, and discussed how to use the open source PhoneGap to interact with a device more deeply than most browsers can. Finally, I discussed AppCache, a way of storing files on a device to allow offline access. We looked at what it does and how to access it with JavaScript, and briefly covered its limitations.