Any active domain that is added in a hosting account has a variety of records that allow it to function properly. In the typical case, the name servers (NS records) show the location where the domain is hosted and they are 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 (using an Internet domain for non-website purposes on a specific port number like Voice-over-IP), etc. By having access to these records and by having the capacity to edit them, you can have your web site with company A and your e-mail messages with company B, for illustration. This offers you more independence since you can select the best provider for each of these services and you don't have to stick with a single company. After you pick a hosting company, you have to make certain that you have access to all DNS records freely because some providers have an additional fee for this feature.