Each registered domain name 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 web hosting company. In this way, you have both your website and your emails handled by the exact same provider. On the lower level of the Domain Name System (DNS), on the other hand, there is a variety of other records, such as A and MX. The former shows which server manages the website for a given domain name and is always an IP address (188.8.131.52), while the latter indicates which server manages the e-mails and is always an alphanumeric string (mx1.domain.com). For example, when you enter a domain in your browser, your request is forwarded 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 provided you have set an IP address of the latter as an A record for your domain. Having different records for the site and the emails suggests that you can have your website and your emails with 2 different providers if you'd like.