Every registered domain has at least two 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 specific website hosting provider. That way, you have both your website and your e-mails handled by the very same service provider. On the lower level of the Domain Name System (DNS), nevertheless, there are a number of other records, for instance A and MX. The first one shows which server manages the site for a given domain and is always an IP address (18.104.22.168), while the latter indicates which server manages the emails and is always an alphanumeric string (mx1.domain.com). For example, whenever you enter a domain name in your browser, your request is sent through the global DNS system to the company whose NS records the domain name uses and from there you will 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 domain address. Having separate records for the site and the e-mails means that you can have your site and your e-mails with two different companies if you wish.