computer networks – Why does diskless system doesn’t contain IP address?

I am studying about RARP.

What is the IP address of a given hardware address? Used by diskless systems to find their own IP address.

So, why do diskless system doesn’t have IP address? What does it even mean to be a diskless system?(Is it hard disk less system). If so, why does that mean that device doesn’t have IP address? Is IP address assigned based on hard disk?