What causes page faults?

Question

According to Wikipedia:

A page fault is a trap to the software raised by the hardware when a program accesses a page that is mapped in the virtual add

Answer 1

You'll see soft page faults when memory is being shared between processes. Basically, if you have a memory-mapped file shared between two processes, when the second process loads the memory-mapped file, soft page faults are generated - the memory is already in physical RAM, but the operating system needs to fix up the memory manager's tables so that the virtual memory address in your process points to the correct physical page.

Particularly for something like Process Hacker, which is likely injecting code into every running process (in order to collect information) it's likely making quite heavy use of shared memory for doing IPC.