A subdomain is part of a domain in the Domain Name System. It is highlighted as a prefix and separated by a period. The subdomains are intended to best guide the user through the website. They are not integrated but imposed by the server. Through the use of a subdomain, the server is better structured and more transparent.
Subdomains can be used when different products need to be separated. For example, Google offers services such as Gmail or Google Docs. These are added as subdomains. They also play an important role when pages on a website differ significantly from the actual content. This is particularly the case when a web page exists in several languages. Also note when when using a subdomain, the www is omitted.
French version: http://fr.mylocationip.com
Spanish version: http://es.mylocationip.com
The importance of subdomains has increased dramatically since Google only allows two results per host in its rankings. This therefore benefited websites that already had subdomains. It was therefore also possible to gain several places in the rankings, and in particular in the first ten places, which ensured significantly more traffic. Today, subdomains play an important role in ranking, although they have now been grouped together by search engines.
A subdomain provides the ability to logically divide large corporate or organizational websites. For example, a large hotel chain might assign each hotel its own subdomain and structure information such as prices, photos, captions differently, so that the user can navigate it even better.
Due to the orderly function of subdomains, they are often confused with subdirectories. For SEO optimization, subdomains that are not linked to main domains are as important as subdirectories. Although they are not directly ranking factors, they do play a major role. It's up to the webmaster to decide which of the two he prefers to use. The differences in the configuration and selection of the content management system must be taken into account here in particular.
Unlike subdomains however, no Domain Name System is needed for subdirectories. Also, it's easier to change the domain of a blog through a subdirectory. A change of domain is possible and only requires the acquisition of a new domain and subdomain.