In Windows, how many unique address spaces are used by applications running in user mode?

Applications running in user mode on Windows each utilize a unique address space. This design allows each process to operate in its own isolated environment, preventing one process from directly accessing or manipulating the memory of another.

This isolation is crucial for system stability and security. When a new process is created, the operating system allocates a distinct address space for it, ensuring that the memory used by this process remains separate from others. Thus, if a process crashes, it does not affect the others since they are operating in their own memory areas.

While there may be a shared kernel mode address space for system-level access, the user mode applications are confined to their individual address spaces, and the number of these spaces corresponds directly to the number of processes that are currently running. Hence, this leads to the conclusion that as many unique address spaces exist as there are processes operating in user mode.