Each registered domain 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 specific web hosting company. In this way, you have both your website and your e-mails managed by the very 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 first one shows which server handles the website for a given domain address and is always an IP address (18.104.22.168), while the second one shows which server deals with the e-mails and is always an alphanumeric string (mx1.domain.com). As an example, any time you enter a domain name in your Internet browser, your request is directed through the global DNS system to the company whose NS records the domain name uses and from there you will be directed to the servers of a different service provider provided you have set an IP address of the latter as an A record for your domain. Having separate records for the website and the emails means you may have your site and your e-mails with two different providers if you wish.