How does Windows detect inactivity before going to sleep?

Question

Iron

It is clear that 15 minutes of inactivity should pass. But how does Windows distinguish them?
If I set the download for example, after 15 minutes the computer will go to sleep?

Answer 1

1. Working with the mouse / keyboard
2.1 Commands from programs that prohibit falling asleep (for example, utorrent)
2.2 System processes (defragmentation)