Think of it as "Your app runs like an operating system". Instead of installing an OS and installing your app on that OS, the OS is a library you use to talk to

Think of it as "Your app runs like an operating system". Instead of installing an OS and installing your app on that OS, the OS is a library you use to talk to the hardware. It's good for two reasons. First security, if you only use the HDD and network, you don't have to include code for display or mouse etc. which could be a security risk. Second, it's faster, because you don't have to do syscalls, since your app IS the OS, syscalls don't need to get out of userspace.