Application Pool:

In IIS (Internet Information Services), each ASP.NET application runs within an application pool.
An application pool is a collection of one or more URLs that are served by a worker process or a set of worker processes.
Each application pool operates independently, and any issues or faults within one application pool do not affect other application pools.
Worker Process (w3wp.exe):

Each application pool is associated with one or more worker processes (w3wp.exe) that handle incoming requests for the applications within the pool.
Each worker process operates independently, serving requests for its associated application pool.
Worker processes are isolated from each other, meaning that issues such as application crashes or memory leaks in one worker process do not affect others.
Process Boundaries:

Each worker process operates within its own memory space and process boundaries.
This isolation ensures that resources, such as memory, CPU, and handles, are allocated separately for each worker process.
If one worker process encounters a problem, such as a memory leak or a crash, it does not affect other worker processes or applications.
Application Domains:

Within a worker process, ASP.NET further maintains isolation using application domains.
Each ASP.NET application within a worker process runs in its own application domain.
Application domains provide a level of isolation within a worker process, allowing multiple applications to run independently without interfering with each other’s memory or state.
Configuration Isolation:

ASP.NET allows configuration settings to be applied at the application level.
Configuration settings such as authentication, authorization, session state, and application settings can be configured independently for each ASP.NET application.
This ensures that each application can have its own configuration settings, tailored to its specific requirements, providing further isolation.