Any active domain name that's added in a hosting account features a number of records which allow it to perform properly. In the general case, the name servers (NS records) show the location where the Internet domain 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 like A (IP address of the website/server), MX (e-mail server), SRV (using a domain name for non-website purposes on a particular port number such as Voice-over-IP), and so on. With access to these records and by being able to edit them, you may have your website with company A and your emails with company B, for example. This gives you more flexibility since you can pick the best provider for every single one of these services and you do not have to stick with only one company. As soon as you select a hosting company, you have to make certain that you can access all DNS records freely since some providers have an additional fee for this function.