Web application vs. Web service

Can anyone summarize the differences between these 2? thanks.

The difference between the two might be fuzzy at the edges, but the basic idea is:

Web application: any application which resides on a server, but meant for use by humans, which uses web pages as the presentation layer. All user interactivity (the GUI) is done through web pages, but all data is stored and (mostly) manipulated on the server.

Web service: server-based application (as above) which may be accessed over the web via HTTP, but is meant primarily for interaction with other programs. Thus, it will have a clearly-defined API which consists of providing responses to HTTP GET and POST requests made by a remote application. Now, this doesn't mean you can't access a web service from your browser, but it means that the application won't necessarily have a GUI user interface. You will most likely, for example, receive all results of GET and POST requests as strings of XML, which requires a client-side parser.

So, think of web applications as completed user interfaces, while web services are more intended to be application components or "libraries" which can be used by other applications. Essentially, web services are to distributed applications what DLLs or class libraries are to most traditional compiled applications.

Also, this means that a web service has to have a more organized design that most web applications, because there won't necessarily be a human at the other end who can figure out through trial and error what the app does. This is why the whole concept of "web services" has brought a whole new set of acronyms such as SOAP, UDDI, etc...

(pauses for breath)

And furthermore--

(hooked cane reaches out and grabs rycamor off stage)

awesome summary. Thanks