Any active domain name which is added in a hosting account has a variety of records that enable it to perform properly. In the general case, the name servers (NS records) show the location where the domain name is hosted and they're 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 specific port number like Voice-over-IP), etc. By having access to these records and by having the ability to edit them, you may have your web site with company A and your emails with company B, for illustration. This gives you more flexibility as you can pick the best provider for every single one of these services and you do not have to stick to one company. After you select a hosting company, you have to make certain that you have access to all DNS records freely because some companies have an additional fee for this feature.