You can read about IP addresses in more detail here but basically it is the numerical ‘address’ of every server or computer(s) connection linked to the Internet:

Why it’s significant for SEO is that we are trying to mimic viral popularity online and genuine viral popularity does NOT mean having most links coming from ONE server in ONE datacenter in ONE city in ONE country.

For example, a mega-popular site like taylorswift.com

has links from EVERYWHERE in the world (MANY different datacenters, countries and IPs):

And we are replicating that on a smaller scale with our PBNs, probably built with domains sourced from our Bluechip Backlinks platform (world’s cheapest quality expired domains there in Bluechip Backlinks, $6-$11 each).