Every registered domain has no less than 2 Name Server records which show where it is hosted i.e. by using these records you point your domain name to the servers of a specific hosting company. In this way, you have both your website and your e-mails managed by the same company. On the lower level of the Domain Name System (DNS), nevertheless, there are a number of other records, for example A and MX. The first one reveals which server deals with the site for a given Internet domain and is always an IP address (18.104.22.168), while the latter shows which server manages the e-mails and is always an alphanumeric string (mx1.domain.com). As an example, any time you type a domain address in your web 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 directed to the servers of a different provider if you have set an IP address of the latter as an A record for your domain. Having independent records for the site and the emails suggests that you could have your website and your emails with 2 different companies if you wish.