Each registered domain has no less than two Name Server records which show where it is hosted i.e. by using these records you point your domain to the servers of a particular website hosting company. This way, you have both your website and your e-mails managed by the exact same company. On the lower level of the Domain Name System (DNS), on the other hand, there are a number of other records, for example A and MX. The former reveals which server manages the website for a given domain address and is always an IP address (18.104.22.168), while the second one indicates which server deals with the e-mails and is always an alphanumeric string (mx1.domain.com). As an example, when you type a domain in your Internet browser, your request is sent through the global DNS system to the company whose NS records the domain uses and from there you will be sent to the servers of another company if you have set an IP address of the latter as an A record for your Internet domain. Having different records for the website and the emails suggests that you may have your website and your emails with two different providers if you would like.