Web, domains and email
CNAME
Abbreviation for Canonical Name
In short and in plain language
A CNAME record is an entry for a domain. It says: this name points to another name.
It sits in the address book of the internet.
It is often used for parts of a domain. For example, an outside service should be found under your own address.
Definition
A CNAME record is a DNS entry that makes one domain name an alias pointing to another name. It is often used for subdomains, for example when an external service should be reachable under an address of your own domain. Whether a service needs such a record is stated in its instructions.