It's also nice to be able to selectively cache some data offline so that users aren't greeted with a "you are offline" screen when they hit your web page withou

It's also nice to be able to selectively cache some data offline so that users aren't greeted with a "you are offline" screen when they hit your web page without a network connection. For an e-commerce website, this might be the user's shopping cart and favorites. For a note taking app, this might be the last note the user edited. For a Twitter client, this might be the user's drafts and the last 100 tweets on their timeline. This way, the app can say "you're offline, but you can still look at some of this data and do things with it, and we'll sync you up when you get back online". Native apps already do this. E.g, try posting a picture to Instagram while you're offline.