Any active domain name that's added in a hosting account includes a variety of records which allow it to work properly. In the typical 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 set through the hosting company like 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. With access to these records and by being in a position to edit them, you can have your website with company A and your e-mail messages with company B, for example. This offers you more flexibility since you can choose the best provider for each of these services and you don't have to stick with one company. When you select a hosting company, you have to make certain that you have access to all DNS records freely as some companies have an extra fee for this feature.