The Internet address of a website is referred to as the domain. Each web page is assigned a domain name. If you enter this domain name in the address line of the browser, the web page will be accessed. A domain name is composed of several elements that are separated from each other by periods.
The so-called top level domain is the domain ending, i.e. the last part of the Internet address. There are different domain endings to choose from depending on the homeland of the site operator and the type of organization behind the website. American websites usually end in the top level domain .com. In addition, there are many other top level domains, such as .net, .org, or .info. The endings .mil and .gov are specifically reserved for military or government institutions. The ending .edu is used for educational facilities in the U.S.
The actual name of the website forms the second level domain. Within the domain name www.serpyou.com, the name "serpyou" is the second level domain. A domain that is below this second level domain in the hierarchy, such as is the case with "adsense.google.com," is referred to as a third level or also sub-level domain.
The "www" at the beginning of the domain name is the abbreviation for "World Wide Web." It is not always necessary to enter "www" to access a site.