More and more professionals rely on IP intelligence sources such as IP Netblocks WHOIS Database to learn more about IP addresses and their ranges (consecutively numbered sets of IP addresses). Many, however, do not have a full understanding of how IP netblocks and addresses are broken down in the first place and why this information can be useful.
Essentially, IP addresses are numbers from 0 to 536,870,911. Their distribution amongst users is done by Classless Inter-Domain Routing (CIDR). The idea is that the whole interval is split into parts assigned to different bodies responsible for them. These bodies will then split their IP address intervals into smaller ones and delegate their administration to other bodies or end-users. So finally the smallest intervals will have actual owners, or, vice versa, owners will have one or more intervals.