What is a domain name?

Think of a domain name as a namespace (family name/umbrella/container) which has services linked to it (email/website/cloud data/messaging). The domain name is there to consolidate (group) the services under an identity.

Each service can be hosted by a completely separate service provider, if necessary. In order to know which servers to connect to, other computers on the Internet he information as to which service provider's server(s) host each service, must be available for other computers on the Internet.

Every domain has a database (directory/address book) which tells other computers on the Internet which servers