A subdomain is a subsection of a website that is identified by a second domain name. The most common use for subdomains is to host different content on different parts of the same website.
This can be done for a variety of reasons, such as localization (having a version of the website in another language), creating separate identities for different brands or products, or serving specific types of content (such as images or videos) that are not found on the main website. In some cases, subdomains differentiate between sections of a website that have similar purposes but are operated by different teams or individuals.
For example, on the website www.example.com, the subdomain www.example.com/blog might be used to host a blog written by members of the website's staff. Similarly, www.example.com/store could be used to sell products related to the content on the main website, while www.example.com/support provides customer support for the website's visitors.
You can create subdomains for any existing domain name, and they are often used to organize different types of content on a single website. Many companies use subdomains to provide a more customized experience for their users, and they are an effective way to keep a website organized and easy to navigate.