Glossary
Custom domain
A custom domain is a domain name (yourbrand.com) you own and point at a hosted product, instead of relying on the host's default subdomain.
A custom domain is the brand-owned URL where your website lives. Most hosts give you a free default subdomain (e.g. yoursite.netlify.app, yoursite.websitekiller.com); using your own domain (yourbrand.com) replaces the default with the URL you actually want users to see.
Connecting a custom domain typically means either pointing your apex (yourbrand.com) and www subdomain at the host's nameservers, or adding A/CNAME records pointing at the host's IP/hostname.
Custom domains improve brand trust, branded SERP results, email deliverability when paired with the same domain, and SSL identity.
Example
Switching from yoursite.websitekiller.com to yourbrand.com typically improves direct traffic and branded search clicks within 2–4 weeks of indexing.