Every registered domain name has a minimum of two 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 certain hosting company. In this way, you have got both your site and your e-mails handled by the same service provider. On the lower level of the Domain Name System (DNS), however, there are a number of other records, like A and MX. The former reveals which server handles the website for a given Internet domain and is always an IP address (188.8.131.52), while the second one shows which server handles the emails and is always an alphanumeric string (mx1.domain.com). As an illustration, when you type a domain name in your web browser, your request is forwarded through the global DNS system to the provider whose NS records the domain address uses and from there you will be forwarded to the servers of a different company in case you have set an IP address of the latter as an A record for your Internet domain. Having independent records for the website and the e-mails means that you can have your site and your emails with two different companies if you would like.