what is hostuuid, hostid (for)?

[Sandra Kachelmann]

I just setup a new server with 7.0-RELEASE and saw the following lines
for the fist time when booting the system:

Setting hostuuid: 2231232f-4000-aaaa-2333-aafbb88a88ca.
Setting hostid: 0x89e3310b.

What exactly are those for? Is it a unique string based on my hardware
based on a certain component? CPU maybe? Is it something that could be
determined under lets say Linux as well? I am asking because this
could become handy as a unique identifier for a piece of equipment
(for putting it on stock, re-using, inventory database, ...).

Sandra