At the core of a URL is the domain name. The purpose of the domain name is to identify the website and distinguish it from all others. If a domain name is already in use by one organization or individual, it will not be available to others unless the registrant sells the rights to it or does not renew their registration.
You can recognize the domain name by looking at the first part of the URL. URLs start with a protocol identifier, usually http or https, followed by a colon and two slashes (://). The next section of the URL, which will precede any other slashes, will end with the domain name. The domain name consists of two parts:
The second level domain may be preceded by a subdomain. The most widely used subdomain is www, but you've most likely noticed many others. If you access your e-mail on the Web, you have probably seen subdomains such as mail.yahoo.com, mail.google.com, or imail.losrios.edu. Subdomains sometimes refer to an actual computer that is being used to store the pages, but in most cases they are used to distinguish different sections of a website from each other.
Following the top level domain you will often see a slash followed by other letters and/or numbers. This is the document path, In some cases the path might end with a document name ending in a file extension, such as html, php, xml, or pdf, but often it will not. The path shows the way the page is organized in relationship to others; it is similar to the way you put files in folders (or directories) on your own computer's hard drive. Sometimes this part of the URL can help you see what section of the site you are located in. The image below shows you a sample URL with its various parts identified.
If you are able to find the domain name, you can always find your way back to a site's home page, even if there is no link to it on the page. Simply go to your browser's address bar and delete everything following the domain name and you should arrive at the main page for the site; if the URL contains a subdomain, eliminate it and you should be taken to the main page for the site as a whole. Once you have found the home page, you should be able to locate important information (such as an "about" page) that will help you evaluate the site.
As we'll see in the next couple pages, you can also use the domain name to find out more information about the website.