Why do folders have permissions and ownership?

I'm more of a Linux girl so I'm not as familiar with Windows-specific permissions, but this idea of hierarchy of trust is actually a pattern that repeats itself in many different layers of a modern OS. File Permissions are, to big extent, actually a feature of the filesystem rather than the OS itself- while a modern NTFS partition on Windows will use an Access-Control List to indicate who can read or write to a file (which can be connected to Active Directory stuff in a commercial environment), if you try to set such permissions on a FAT32 partition (such as on an old thumb drive), the feature is actually not implemented in the same way, and you likely won't be able to mark a specific user as the only one allowed to read a file. While a computer that is only used by 1 person may not see much direct use out of file permissions, this feature can still come into play in situations happening outside the user's view. For instance, the Flatpak system on Linux actually sets file permissions on individual programs, preventing them from acting in places where they are not expected to, intending to make it harder for a compromised program to explore the computer or make unauthorized changes. This pattern also happens in the CPU- there, it's called Protection Rings, and processes are assigned different rings depending on how important they are. The User the person is using is actually given the least amount of trust here- the x86 architecture used in modern computer has 4 rings of trust- the OS kernel runs in Ring 0, the User is put in Ring 3, and while a lot of OS's don't take advantage of Rings 1 and 2, those are meant to host device drivers and other things that need permission to access low-level hardware functions. A real-world impact of this you've probably experienced is computer crashes: when a Ring 3 program breaks and crashes, execution is stopped, the application typically closes on your screen, and any resources it claimed are released back to the system, allowing you to try restarting the program- this forgiveness is included in the lack of trust. In comparison, if a program in Ring 0 breaks, by definition the system is designed to assume that mission-critical functions have failed, and will not even attempt to recover itself, instead proceeding to the crash handler- the old BSOD nobody ever wants to see. You are right that companies will go much further than just setting file permissions when it comes to securing data, but they also don't rely on any single tool for the whole plan- but I'm starting to get off topic here. Some further reading that might interest you, if you're wanting to dive deeper into the topic of file access control: [https://en.wikipedia.org/wiki/Access-control\_list](https://en.wikipedia.org/wiki/Access-control_list) And regarding the people here- yeah, they tend to expect sysadmins here talking to fellow sysadmins about topics specifically tied to their work. Being a fly on the wall, a lot of them are pretty burned out from their jobs, and they made the assumption that you were a sysadmin rather than a visitor with a question. I think the folks over at r/AskComputerQuestions tend to be friendlier in regards to lower-level questions like yours. I hope this helps!