A subdomain in WordPress is a domain that is a part of a larger domain or website. It is a separate domain that is used to create a separate website or section of a website, but it still uses the main domain name as its base.
For example, if your main website is www.example.com, you can create a subdomain such as blog.example.com or shop.example.com to create a separate section of the website for a blog or online store.
In WordPress, you can create a subdomain by setting it up in your domain registrar and then creating a subdomain installation of WordPress. This allows you to create a completely separate website with its own content, design, and functionality while still being part of the larger website.
Using subdomains in WordPress is a popular way to organize and structure a website, especially if you have multiple sections or areas that require different functionality or design.