In layman’s terms, an application pool in IIS (Internet Information Services) acts like a container or a separate workspace where your web applications run. Think of it as a private room where a specific website or application operates, isolated from others to ensure stability and security.

Each application pool has its own w3wp.exe process, which is the worker process responsible for handling web requests. By isolating applications into different pools, you can ensure that if one website or application encounters an issue, it won’t affect others. This setup is especially useful for hosting multiple applications on the same server.

For example:

• If one application crashes or uses too many resources, it won’t bring down the others because they’re running in separate pools.
• Different application pools can have unique settings, like memory limits or specific .NET versions.

This isolation also enhances security and scalability, making IIS a robust choice for managing web applications.

To learn more about w3wp.exe and how IIS application pools work, you can check out this detailed guide:
👉 What is w3wp.exe in IIS Worker Process?