How to create subdomain in cpanel

It is not always necessary to register a new domain name if you already have one and you are interested to have a separate site apart from the main one.
Rather than registering a new domain name, you can always create a subdomain using a domain you already own, for example blog.domain.tld or forum.domain.tld (assuming you already hold domain.tld). You can also add multiple levels of subdomains, for instance info.blog.domain.tld.
Subdomains are extensions of your domain name that you can forward to URLs or point to IP addresses instead of purchasing additional domains. Usually, they are used for segmentation or verification of different services associated with a domain name.