A domain is used to refer to an internet address. When you type a domain name into your browser, it will automatically load content from that hosting. There are three levels or tiers of domains. The first level is a domain name such as .com, .net, .org, .fr, .de. Second level domains are paid and registered because they already contain a specific site name, such as google.com. The third level of domain is called a subdomain, which consists of the subdomain name and the domain, it can be in the form of some-subdomain.domain.com.