Every registered domain name has at least 2 Name Server records which show where it is hosted i.e. by using these records you point your Internet domain to the servers of a certain hosting company. This way, you have both your website and your e-mails handled by the exact same company. On the lower level of the Domain Name System (DNS), however, there is a variety of other records, for instance A and MX. The former shows which server handles the website for a given domain and is always an IP address (123.123.123.123), while the second one reveals which server manages the emails and is always an alphanumeric string (mx1.domain.com). As an example, when you type a domain address in your browser, your request is directed through the global DNS system to the provider whose NS records the domain uses and from there you will be forwarded to the servers of another company provided you have set an IP address of the latter as an A record for your domain address. Having different records for the website and the emails suggests that you can have your website and your emails with 2 different providers if you wish.