inet6num: 2001,ac0,30fd,,/48 netname: BT-ES-AS12541-INFRA descr: BT Spain AS12541 infrastructure country: ES admin-c: RM13024-RIPE tech-c: RM13024-RIPE status: ASSIGNED mnt-by: BTTEL-MNT mnt-lower: BTIGS-MNT mnt-routes: BTIGS-MNT created: 2012-03-12T08,59,05Z last-modified: 2016-05-26T06,57,44Z source: RIPE person: Raul Mateo address: BT Spain address: Isabel Colbrand, 8 address: 28050 MADRID address: SPAIN phone: +34 91 270 6234 fax-no: +34 91 270 6310 e-mail: email@example.com nic-hdl: RM13024-RIPE mnt-by: BTTEL-MNT created: 2012-03-07T14,40,19Z last-modified: 2012-03-07T14,40,19Z source: RIPE route6: 2001,ac0,30fd,,/48 descr: BT SPAIN AS12541 INFRA aggregated route notify: firstname.lastname@example.org origin: AS12541 mnt-by: BTIGS-MNT created: 2012-03-12T09,04,38Z last-modified: 2016-05-26T06,50,04Z source: RIPE
IP address ranges, or netblocks, are groups of related IP addresses. They are usually represented as a base IP address, followed by a slash, and then a netmask which represents how many IP addresses are contained within the netblock. This format is known as CIDR. You'll also sometimes see netblocks given as a start ip address, and an end ip address, or an ip address range.
Traffic works its way around the internet based on the routing table, which contains a list of networks and their associated netblocks.