Domains can be registered up to 10 years. Once the domain expires you have up to 45 days to renew it at your renewal rate. During this period your website and email will continue to work. After this period the domain goes into a redemption grace period, which lasts 30 days, where you can still renew the domain but with a stiff penalty. During this period the website and email will cease to work. In addition, during the redemption grace period domain backordering companies are notified of the domain. These companies offer the domain to their clients utilizing a bidding process.
After the redemption grace period the domain goes into
a pending delete status, up to 5 days, which is the last chance to
backorder the domain. If nobody bids on the domain during the redemption
grace period and pending delete period then the domain will be a
deleted domain and available to purchase from any domain provider.
DeletedDomains.com is the ultimate tool for uncovering both "on hold/expiring" domains and "deleted" domains. Unlike other services that simply offer a list that is updated once or twice a week, Deleted Domains updates their database at least once each day, meaning it is the most up-to-date service of its kind.
Best of all it's free!