Every registered domain has no less than 2 Name Server records that show where it is hosted i.e. by using these records you direct your Internet domain to the servers of a particular hosting provider. That way, you have got both your site and your e-mails managed by the exact same company. On the lower level of the Domain Name System (DNS), nevertheless, there are a number of other records, for instance A and MX. The former reveals which server manages the site for a given domain name and is always an IP address (18.104.22.168), while the latter 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 address in your web browser, your request is directed through the global DNS system to the provider whose NS records the domain name uses and from there you could be sent to the servers of a different provider in case you have set an IP address of the latter as an A record for your domain name. Having different records for the website and the emails means that you could have your site and your e-mails with 2 different providers if you'd like.