📌 Note: Attaching a subdomain other than "www" is only possible when you're managing your own domain.
Subdomains are the text strings before your main website domain. For example, in https://www.nationbuilder.com, "nationbuilder" is the domain, and "www" is the subdomain.
Having "www" as the subdomain is fine for most sites, but if you'd like a different subdomain or have multiple sites for which you'd like to use the same domain, you can set that up in NationBuilder as follows:
Navigate to Settings > Domains.
Hover over the site for which you'd like to modify the subdomain, then select "Edit."
Navigate to Sites > Edit again, select "Remove Subdomain" and select "OK."
Select "Attach one here."
Add your custom subdomain and select the website to which you'd like to attach it.
Click "Save."
Congrats, your custom subdomain is created!