All domain names have a date listed of when their registration expires. A domain name can be registered from 1 to 10 years.
Expired Status (40-45 days): If the owner of a domain does not renew by the expiration date of the domain, the domain goes into "expired" status. As soon as the domain becomes expired all services are shut off that rely on that domain name's DNS resolving to work (website, email, FTP, etc). The domain name enters into a grace period - typically 40 days - in which the domain name owner may still renew the domain, usually for the standard renewal fee.
Redemption Status (30 days): At the end of the "expired" period, the domain name enters a "redemption period." All WhoIs information is removed, and should the domain owner/former owner wait until the redemption period to pay for and keep the domain, there are additional fees (upwards of $100) associated with renewal.
Locked and Deletion Pending Status (5-10 days): After the redemption period has ended, the domain’s status will change to "locked" as it enters the deletion phase. The deletion phase is 5 days long, and on the last day between 11am and 2pm Pacific time, the name will officially drop from the ICANN database and will be available for registration by anybody.
The entire process takes 75-90 days after the listed expiration date.