A second-level domain is the next highest level of the domain name hierarchy after the top-level domain. In a domain name, it is the alphanumeric string immediately to the left of the top-level domain, separated from it by a dot. Second level domain names are often the name of the organization which owns the domain name, e.g., microsoft.com.
|“||Second-level domain names, the name just to the left of ‘.com’, must be exclusive. Therefore, although two companies can have non-exclusive trademark rights in a name, only one company can have a second-level domain name that corresponds to its trademark. * * * In short, the exclusive quality of second-level domain names has set trademark owners against each other in the struggle to establish a commercial presence on the Internet, and has set businesses against domain name holders who seek to continue the traditional use of the Internet as a non-commercial medium of communication.||”|
"Some specific 'vulgar' words and a few words that are prevented by federal statute from being used by private entities are not available as SLDs."