Any active domain that is added in a hosting account includes a variety of records that enable it to work properly. In the general case, the name servers (NS records) show the location where the Internet domain 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 such as A (IP address of the website/server), MX (e mail server), SRV (employing a domain address for non-website purposes on a specific port number like Voice-over-IP), and many others. Having access to these records and by having the ability to modify them, you can have your website with company A and your e-mail messages with company B, for instance. This gives you more flexibility as you can select the best provider for every single one of these services and you do not have to stick to only one company. After you choose 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.