Every single registered domain name has a minimum of 2 Name Server records which show where it's hosted i.e. by using these records you point your Internet domain to the servers of a particular web hosting provider. In this way, you have got both your website and your emails handled by the very same provider. On the lower level of the Domain Name System (DNS), however, there are a number of other records, for instance A and MX. The first one reveals which server manages the site for a given domain address and is always an IP address (188.8.131.52), while the second one indicates which server manages the emails and is always an alphanumeric string (mx1.domain.com). As an example, when you enter a domain address in your Internet browser, your request is directed through the global DNS system to the company whose NS records the domain uses and from there you will be forwarded to the servers of another provider in case you have set an IP address of the latter as an A record for your domain. Having separate records for the site and the e-mails means that you could have your website and your e-mails with two different companies if you'd like.