Every store starts on a platform subdomain — it always works and cannot be removed. Settings → Domains is the domain inventory in the web admin and mobile apps: add custom domains, review their DNS records, verify them, and remove domains you no longer need. Assign an active domain and choose the primary address from that storefront's Domains tab.
Domain types
Subdomain — your built-in address on the platform. Custom domain — a domain you own, connected by adding DNS records at your domain provider and verifying. Each store can hold a limited number of custom domains; the counter on the page shows your usage.
Storefronts and languages
An active custom domain can be assigned to a storefront from the storefront's Domains tab, and — on Advanced and Plus plans — a domain can be pinned to serve a specific published language.
Domains and email
A verified domain can also be registered for email sending in Settings → Email. A domain that's in use for email (or has sender addresses on it) must be removed from Email settings before it can be deleted here.