|ASN||AS14618 Amazon.com, Inc.|
Netblocks are groups of related IP addresses. They are usually represented as a base IP address, followed by a slash, and then a 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.