The one most domain owners meet is the auto-renew grace period. When a gTLD domain reaches its expiry date, the registry automatically renews it for a year and gives the registrar up to 45 days to delete it again for a refund. During this window the registrar typically lets the owner renew at the normal price, although it may already have pointed the domain to a parking page or suspended its DNS. How many of those days the customer actually gets is the registrar's decision and is often shorter than 45.
This is why the expiry date in a lookup can jump forward by a year just after a domain expired: the registry has auto-renewed it, but the owner may not have paid. The status autoRenewPeriod marks that situation.
There is also an add grace period of five days after a new registration, during which a registrar can delete the name for a refund, plus renew and transfer grace periods that work the same way. After the grace period, a deleted gTLD name enters the redemption period. Country-code TLDs define their own windows.