Define “web application”
What essentially defines a web app? Are all useful websites web apps?
As examples, is Google search a web app? G-mail? Wikipedia?
I think that in one phrase it can be defined as an application that you run and access through your browser.
I guess that the difference with a "basic" website would be that the website aim is mostly to display information and not really interact with the user.
Of course the definition is not really precise. For some application it is quite obvious (as for most of Google products, facebook...), but for others it may depend on your own interpretation.
I'd cite some definitions found on websites :
Web Apps - Stack Exchange is for expert and advanced users of web applications, so if your question generally covers …
* Gmail * Facebook * Twitter * Google
… or any other website which behaves like an application, then you're in the right place to ask your question!