A country code second-level domain is a second-level domain to a country code top-level domain. Such a domain may be reserved by a domain name registry for the registration of third-level domains, or assigned to a third party as a subdomain.
Many country code domain registries implement domain name classes at the second level underneath their ccTLD, such as are present in the original generic top-level domains,, and, which were intended for commercial entities, network operators, and non-profit organizations, respectively.
Many countries implement additional classes. For example, the United Kingdom (.uk) uses for commercial purposes and for academic registrants. Brazil (.br) has a high number of predefined second-level domains, 140 as of 2021; they range from for commercial activities and for veterinarians to for wikis (see .br § Second-level domains).[1]