Help: What do these domain name suffixes mean? In what field? Can you explain it in detail

The first basic type of name is international domain (iTDs), also known as the international top-level domain name. This is also the earliest and most widely used domain name. For example, Industrial and commercial enterprise network. Net to network providers. Org is a non-profit organization. Second, domestic domain names, also known as national top-level domains (nTLDs), that is, different suffixes are assigned according to different countries, and these domain names are the domestic top-level domains of that country. At present, more than 200 countries and regions have allocated top-level domain names according to ISO3 166 country codes, such as cn in China, us in the United States and jp in Japan. See below for details. In actual use and function, there is no difference between international domain and domestic domain names, which are unique signs on the Internet. Only in the final management organization, international domain is registered and managed by ICANN, the Internet Corporation for Assigned Names and Numbers authorized by the US Department of Commerce; Domestic domain names are registered and managed by China Internet Network Information Center (CNNIC). Edit the domain name level of this paragraph. Domain names can be divided into different levels, including top-level domain names and second-level domain names. Top-level domain names are divided into two categories: one is national top-level domain names (nTLDs). At present, more than 200 countries have allocated top-level domain names according to ISO3 166 country codes, for example, China is cn, the United States is us, and Japan is jp. The second is the international top-level domain name (itd), such as. Industrial and commercial enterprise network. Net to network providers. Org is a non-profit organization. At present, most domain name disputes occur under com top-level domain names, because most companies go online for profit. In order to strengthen domain name management and solve the shortage of domain name resources, international organizations such as Internet Society, Internet Address Organization and World Intellectual Property Organization (WIPO) have extensively solicited opinions, and on the basis of the original three international top-level domain names: (com), Seven new international top-level domain names have been added: firm (companies), store (sales companies or enterprises), Web (units that highlight WWW activities), arts (units that highlight cultural and recreational activities), rec (units that highlight entertainment and leisure activities), info (units that provide information services) and nom (individuals), and new registration agencies have been selected to accept domain names worldwide. Second-level domain name The second-level domain name refers to the domain name below the top-level domain name. Under the international top-level domain name, it refers to the online name of the domain name registrant, such as ibm, Yahoo, Microsoft and so on. Under the national top-level domain name, it is a symbol indicating the registered enterprise category, such as com, edu, gov, net, etc. The top-level domain name officially registered and operated by China in the Internet Information Center (Inter NIC) is CN, which is also the first-level domain name of China. Under the top-level domain name, China's second-level domain names are divided into category domain names and administrative domain names. 6 domain names * * *, among which scientific research institutions use AC; Com industrial and commercial financial enterprises; edu； For educational institutions; Gov for government departments; Net; Internet information center and operation center; Org is a non-profit organization. There are 34 administrative domain names, corresponding to provinces, autonomous regions and municipalities directly under the central government. The third-level domain name is composed of letters (a ~ z, a ~ z, uppercase and lowercase letters, etc. ), numbers (0 ~ 9) and connectors (-). Domain names at all levels use real dots (. ), and the length of the third-level domain name cannot exceed 20 characters. If there is no special reason, it is suggested to use the applicant's English name (or abbreviation) or Chinese phonetic name (or abbreviation) as the third-level domain name to keep the domain name clear and concise. Country code domain name The country code is a two-letter top-level domain name, such as. cn，。 Britain,. Dehe Jp, known as country code top-level domain names (ccTLDs), among which. Cn is a unique top-level domain name in China, and its registration is managed by CNNIC. A second-level domain name ending in. Cn is abbreviated as domestic domain name. The rules and policies of registering second-level domain names under the national code top-level domain name are related to the policies of different countries. When registering, you should consult the domain name registration agency and ask about the relevant registration conditions and terms. Some domain name registrars not only provide registration services for domain names ending in. com，。 Net and. Org, but it also provides the registration of country code top-level domain names. ICANN does not explicitly authorize registrars to provide country code top-level domain name registration services.