For me a web app is an HTML5 web page, that has its interaction logic coded in JS and presentation is done by altering HTML5 DOM and where JS uses REST to send/

For me a web app is an HTML5 web page, that has its interaction logic coded in JS and presentation is done by altering HTML5 DOM and where JS uses REST to send/receive data. In other words as someone else noted, it is a sandboxed application with sandbox execution environment == browser IO == REST UI = HTML5 DOM manipulation of the same page A website (or server app) is a series of HTML5 web apps or HTML5 static pages (JS-less web apps) with navigation logic and inter-app state living in a server app.