When a domain reaches its expiry date, its status will be changed from ACTIVE to EXPIRED and it will remain as EXPIRED for 30 days, during this period of time, the domain will no-longer resolve to the nameservers, the domain holder can still renew the domain during this period.
After that the domain status will be changed from EXPIRED to REDEMPTION and it will remain like that for another 30 days, after that the domain will be deleted from the DNS system and it will be available for new registrations. Please note that during the REDEMPTION period the domain holder can renew the domain with no fees.