TLD .com
.com is arguably the most common top level domain name on the web. Originally it meant "commercial" and was meant to be used by the commercial organisations, but today it is considered to be one of the "default" domains; another .biz domain was created more recently in an attempt to remove the ambiguity.
The .com registry is run by Verisign, alongside .net; they obtained these registries by acquiring Network Solutions, the original registry and registrar chartered by the U.S. government to operate registration for .com, .org, .net, and .edu, though .org and .edu were spun off to other registries. The registrar function, which deals directly with customers registering domains, is decentralized so you can register the domains through many different registrars, all of whom deal with the registry.
Some countries create a second level domains that are analogous to .com. For example, in Britain you can get .co.uk and in Russia ".com.ru" domains. Although they may look similar to some, technically they have nothing to do with .com.
The phase "Dot Com" has also become synonymous with an internet business.
