Each registered domain name has no less than 2 Name Server records which show where it's hosted i.e. by using these records you point your Internet domain to the servers of a particular web hosting provider. In this way, you have got both your site and your e-mails handled by the very same provider. On the lower level of the Domain Name System (DNS), nevertheless, there are lots of other records, for example A and MX. The first one reveals which server handles the site for a given domain and is always an IP address (18.104.22.168), while the latter reveals which server deals with the emails and is always an alphanumeric string (mx1.domain.com). For example, when you enter a domain name in your browser, your request is forwarded through the global DNS system to the company whose NS records the domain address uses and from there you may be sent to the servers of another service provider if you have set an IP address of the latter as an A record for your Internet domain. Having independent records for the website and the emails means you could have your site and your e-mails with two different companies if you wish.