Usually, a domain name is not available for re-registration as soon as it expires. Most registrars allow a grace period that can be as short as one or two weeks or as long as a year for registrants to renew expired domain names. The actual grace period can be different for each individual registrar and domain name extension. That is, the grace period for a .com domain name might be different from the grace period for a .us domain name, even at the same registrar.
After the registrar's grace period, most domain names have a redemption period. This period can last from two weeks to 30 days, and, during this time, the current registrant can renew the domain name by paying a redemption fee along with the domain name's renewal fee.
If the current registrant does not renew or redeem the domain name, it might be auctioned. When a domain name is released to a public auction, you can participate and possibly capture the domain name by placing a bid on it.
If the domain name is not renewed, redeemed, or purchased through an auction, it is returned to its registry. The registry determines when the domain name is released again for registration. Once it's released, you can register the domain name through us.