What is a domain?
A domain is the identifying part of a URL or email address that tells the Internet how to find your website or email server. In the following examples, the domain is shown in bold:
https://porkbun.com/products/web_hosting
support@porkbun.com
A domain can be broken down into three parts:
TLD
TLD stands for "top-level domain". TLD's are associated with the end of the domain name. For example, with www.porkbun.com, ".com" is the TLD. Sometimes the TLD are specific to a country and are called ccTLD, or "country-code top-level domain". An example of a ccTLD is .uk or .us. TLD's are maintained by the registry, which manages a database under a given TLD.
SLD
SLD stands for "second-level domain" and appears to the left of the top-level domain with a dot separating the two. In the example of porkbun.com, "porkbun" is the SLD.
Subdomain
Subdomains, sometimes called third-level domains, are any value that comes before the SLD and TLD. With www.porkbun.com, the subdomain is "www". Subdomains can often be created with DNS records and often is an additional part of your main domain name.