When a domain name expires, there is a time period of a little over 60 days when it's not active, but can still be renewed by the current user. During this time period, the domain cannot be taken by anybody else, but in case it isn't renewed, it gets into the so-called Pending Deletion period that lasts five days. This is when ICANN-accredited registrar firms take backorders for such domains. When a particular name is backordered, the registrar will make an attempt to register it for the customer the second it is deleted and available to the public, which gives people a chance to obtain a short and easy to remember domain which may have been used by someone else up until this moment. If the domain is very appealing, a couple of companies may try to register it in the same time and due to the fact that this happens on a first-come, first-serve basis, there is no warranty that a specific person will have that domain name. Nonetheless, employing a backorder service will give you a better chance to acquire a particular domain than when you attempt to register it yourself.