2001:500:18::/48 - AFILIAS-NET6-2
V6NetHandle: NET6-2001-500-16-1 OrgID: AFILI-2 Parent: NET6-2001-400-0 NetName: AFILIAS-NET6-2 NetRange: 2001:500:16:: - 2001:500:2C:FFFF:FFFF:FFFF:FFFF:FFFF NetType: assignment RegDate: 2007-10-29 Updated: 2012-03-20 Source: ARIN OrgID: AFILI-2 OrgName: Afilias, Inc. CanAllocate: Street: 300 Welsh Road Street: Bldg. 3, Suite 105 City: Horsham State/Prov: PA Country: US PostalCode: 19044 Comment: https://afilias.info RegDate: 2018-08-16 Updated: 2018-10-01 OrgAbuseHandle: HEL4-ARIN OrgNOCHandle: NOC11438-ARIN OrgTechHandle: CLEME4-ARIN OrgAbuseHandle: DOWDK1-ARIN OrgTechHandle: VLAAR-ARIN OrgAdminHandle: HEL4-ARIN OrgTechHandle: HEL4-ARIN OrgAbuseHandle: SILZE-ARIN OrgAbuseHandle: CLEME4-ARIN OrgTechHandle: DOWDK1-ARIN OrgAbuseHandle: VLAAR-ARIN OrgTechHandle: SILZE-ARIN Source: ARIN
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.