A hosted zone is a collection of record sets for a particular domain. These record sets include nameserver (NS) records, Start Of Authority (SOA) records, MX records for configuring mail servers. Hosted zones can be public (for routing over the internet), or private (for routing within Amazon VPCs).

As you saw in the How to do it... section, AWS will automatically create a hosted zone for domains registered with the AWS Route 53 domain registrar, along with NS and SOA records.