dare I ask? (Score 1)

A Web Application Server is a piece of middleware that sits above the HTTP (In same process or out of it - your choice) that holds application logic. It would perform the same function as a CGI with a low end WebApplication Server, but instead of spawing a new process for each user, you initialize once and pool your requests. In the Open Source world, Jserv from Java.Apache.org, modPERL and others can perform this basic function. But an Application Server can scale tremendously beyond there and in between, by spreading the load among various servers, adding a transaction monitor to perform two phase phase commits and lots of other functionality. Without getting too technical a high end Web Application Server like our WebSphere Enterprise can check to validate your credit card and simultaneously check inventory to ensure the company has the product in stock. When you get a yes to both of those answers you them "commit" the transaction.

This is a growing area as Web based applications assume more business processes that touch a company's backend systems.

IBM's WebSphere line encompases several Web Application Servers and other Web related software applications.

I hope that helps from the 50,000 foot level.

James Barry
Product Manager
IBM HTTP Servers (Apache) and WebSphere