What are installable web apps?
Installable web apps are a way of making Google Chrome treat certain websites like apps. People can find installable web apps using the Chrome Web Store.
Many installable web apps are hosted apps—normal websites with a bit of extra metadata. You can build and deploy hosted apps exactly as you would build and deploy any web app, using any server-side or client-side technologies you like. The only difference is that you must provide a small manifest file that describes the app.
If you want your app to work especially well offline or to be tightly integrated with the Google Chrome browser, you can create a packaged app. A packaged app is just a web app that the user downloads. Packaged apps have the option of using the Google Chrome Extension APIs, allowing packaged apps to change the way Chrome behaves or looks.