A subdomain is a sub-name defined under your domain that lets you reach any folder in your web space directly.
For example:
your domain is abcltd.com.tr
and you want visitors who type test.abcltd.com.tr to be taken automatically to the test folder of your website.
To do this, you need to create what is called a "subdomain".
After this setup, an FTP user that gives you direct access to that folder will also be created.
