Any active domain name which is added in a hosting account features a number of records that permit it to work properly. In the typical case, the name servers (NS records) show the location where the domain name is hosted and they are set on the side of the registrar company, but on the lower level there are particular records created through the hosting company such as A (IP address of the website/server), MX (email server), SRV (employing an Internet domain for non-website purposes on a specific port number like Voice-over-IP), and so on. By having access to these records and by having the capacity to modify them, you can have your website with company A and your emails with company B, for example. This offers you more overall flexibility because you can choose the best provider for every single one of these services and you don't have to stick to one company. After you select a hosting company, you have to make sure that you can access all DNS records freely since some providers have an additional fee for this feature.