How do you differentiate a web application from websites? It's language/platform agnostic. 
What are the differences between a website and a web application?
web applications;language agnostic;terminology;websites;difference
When I think of a Web site, I think of a series of pages accessed using the traditional request/response model of the Web over HTTP(S) to transition from page to page.  Some Web sites use AJAX to make them a little more dynamic, such as by preventing the page from needing to be reloaded to show new content.When I think of a Web application, I think of a Web site that uses certain tricks to circumvent the limitations of the Web's traditional request/response model and become something that is much closer to the type of programs one would expect to see on the desktop.When I think of a Web site, I think of marketing.  I picture something that may have a web form, or a blog, or content that I would just read.  I don't think of a Web site as something interactive, something that would take input from me other than just clicking on links to other pages.When I think of a Web application, I think of something that requires just as much from me as I expect from it.  I picture Comet-based tools for increasing sales, like live chat software, or CRM systems for managing customer data, or some kind of interactive software on the Internet.In summary, a Web application can be thought of as a cloud-based version of something you might see on the desktop.UPDATE: Web applications also typically involve tracking users of the system in great detail.  They'll most likely require a username and password, but not always.A great example of a Web application is this site, Programmers SE. What's most interesting is that these types of applications go beyond what you would expect to see in a traditional desktop application in that users from all over the world are able to interact with it, access the content, and update it in semi-real time.