When a domain expires, your website and mail service will stop functioning, and no changes can be made to the domain. However, for many TLDs (.co.nz, .com, etc.), you have a period after the actual expiration date during which you can still renew the domain and retain ownership. If you do not renew the domain during this "Grace Period" then the domain will be released back into the public pool of domains. The actual Grace Period timeframe differs depending on the TLD.
Some TLDs, like .nz domains, also have additional Grace Period after registration or renewal where you can cancel the domain within the timeframe and not be billed for the domain.
This is the period after initial registration of a domain that it is possible to cancel the domain without being billed for it.
This is the period after a domain has been renewed that it is possible to to cancel the domain without being billed for it.
This is the period after a domain name has been cancelled or expired that it is possible for the domain name to be restored.
For information regarding grace periods for all other top-level domain names that SiteHost offers for registration, please feel free to contact us by sending an email to support@sitehost.co.nz.