RIR

A RIR is a regional internet registry, they generally service a continent or large regional body of land, and are typically used by very large ISPs or groups that have a specific need for direct IP assignment from the top. Generally you would go to a RIR when you need a large volume of IP addresses or have very specific routing policies that require several ASNs or other resources. RIRs also cost more than LIRs, however.

The major RIRs are ARIN, RIPE, APNIC, AFRINIC and LACNIC