Domain name is a unique human-friendly alphanumeric Internet site (address) identifier that can be converted into an IP address by DNS.
Domain names consist of top level domains (TLD), second level domains, etc. separated by dots.
Domain names are registered by companies, called domain name Registrars. These companies are accredited by the Internet Corporation for Assigned Names and Numbers – ICANN (http://icann.com/) and are empowered to resell these “rights” to other companies (that are called resellers) through their interface (API).