The HTML5 Offline appcache allows you to create an app that works even when the user is offline (it also has some great performance benefits when used well.)

In this article, I take a very in depth (but eminently practical) look at how it works, how you use it, and some common gotchas.

I also introduce a brand new tool, ManifestR, which helps you build an appcache manifest, a vital part of using the appcache.

So, get off(line) with the HTML5 appcache today!