A subdomain is a piece of information added before the second-level domain webmasters use to organize different sections of a website.
An example would be a webmaster who wants to add a subdomain to a domain (examplewebsite.com) to separate the website’s blog from the rest of the content on the primary domain. The top-level domain is the extension (.com), while the second-level domain is the name of the website (examplewebsite).
The webmaster can create a subdomain via their hosting provider’s file manager by entering the desired name of the subdomain in the appropriate field. A common practice for blog subdomains is adding the word blog before the second-level domain. In this case, the blog would be accessible by visiting blog.examplewebsite.com.