How does particle ID work?

How does niagara particle ID work? I am confused about what does particle ID look like and how it is generated. I have an emitter with an Emitter loop duration = 2s, and particle lifetime = 2s.
In my understanding, in the first 2 seconds loop of my emitter, niagara generates several particles. They have ID from 0, 1, 2, 3… etc. What happens if this loop ends? Will all particles regenerate from 0 to max particle number that I set? And what if my particle lifetime is shorter than emitter’s loop duration?

Thanks for any help!

Plz… any help…

Anyone…?