Domain Name Ownership
When someone registers a domain they do not actually own that domain but
rather secure the right to use the domain so long as the registration
continues to be paid for and does not violate a trademark. For this
reason it is best to think of domain names as being rented or leased
rather than owned.
When you perform a whois search on a domain name a query is sent to the
registrar (the company that registered the domain). This company maintains
a database of contact and ownership details. Because this information
is commonly mined by unscrupulous individuals often the information you
find will be incomplete or inaccurate. Nevertheless, a whois search
remains the quickest and most effective way to determine domain name
ownership.
If you are searching for a domain name that is not registered you may get
a message that a given domain name is not found. You may notice some
registrars will indicate that this does not indicate the domain is still
available for registration. The reason for this is that there is some
lag between when a domain name is registered and when the whois database
is updated. Even so, more often that not if a domain name returns not
found in a whois search it can still be registered.