When you finish your IIS 10.0 installation, you will get the default application pools and default web site. The application pool works on worker process or a set of worker processes for one or more websites.
Application pools are used to separate sets of IIS worker process that share the same configuration and application-level boundaries as your web applications. This is a really great feature of IIS and helps us run our web applications.
The benefit of application pools is that if you have an issue with one of the application pools, it will only effect the associated application pool.
Application pools enable us to isolate our web application for better security, reliability, and availability.
Two types of application pipelines are available. We can select integrated mode (supports IIS 7.5 or later versions) or classic mode (IIS 6.0).