Managing IIS applications and application pools
In the earliest versions of IIS, all of the web pages and sites on a given system ran in a single Windows process. This meant that one application, if not written well, could cause issues with other applications. An application with a memory or handle leak would eventually require a restart of the single process (or even a reboot of the server).
In later versions of IIS, Microsoft added the concept of web applications and application pools to IIS. With IIS, a web application is a set of one or more URLs (web pages). For example, the pages for the WWW2.Reskit.Org example that you created in the Configuring IIS bindings recipe are stored in C:\inetpub\www2 on SRV1. You can configure IIS to run different web applications inside of independent worker processes. This means that your default website and the WWW2 site could run inside of totally different worker processes, and issues with one are not going to affect the other.
An application pool is...
