There are two types of domains on, subdomains, and custom domains.

What is a subdomain?

A subdomain is a domain that looks like Every account is required to choose a subdomain when signing up or creating a site, before being able to choose a custom domain.

You might see a form like this on sign up or create site:

Subdomains should be letters and numbers, with no spaces or special characters, and they must be unique. If your choice doesn’t work the first time, keep trying different words until the outline of the field no longer turns red.

What is a custom domain?

A custom domain is a domain that’s been purchased at a domain registrar, such as You can learn more about how to set up a custom domain by reading Using a Custom Domain in our help section.