Domain Name System (DNS)

The domain name system (DNS) is the internet's address book. When someone types your domain name into a browser, DNS looks it up and translates it into the IP address of the server that should respond, because computers route traffic by numbers rather than names.

DNS changes do not always take effect instantly, since updates can take time to spread across the internet. That is why pointing a domain at a new server is a step you plan carefully around launch rather than leaving to the last minute.