On the Internet, "com" is one of the top-level domain names that can be used when choosing a domain name. It generally describes the entity owning the domain name as a commercial organization. Along with the second-level domain name (for example: "whatis" in whatis.com), the top-level domain name is required in Web and e-mail addresses.
The Internet Corporation for Assigned Names and Numbers (ICANN) has overall responsibility for domain names (as well as for Internet Protocol addresses and many other Internet parameters). Day-to-day responsibility is delegated to specific registrars, such as Network Solutions and a number of competing companies for .com, .org, .net, and .edu top-level domains.
Specific criteria are set forth for the use of the top-level domain name in RFC 1591 - Domain Name System Structure and Delegation.
The top-level domain names administered by ICANN and its delegate agencies are: com, edu, gov, int, mil, net, and org. In addition to these, domain name applicants within the United States may also be able to register a name under a U.S. top-level domain name based on geography. See RFC 1480 - The US Domain and visit the U.S. Domain Registry for registration procedures.
Top-level domain names for countries other than the United States are administered by each country and are based on the ISO-3166 list of country codes.