Any active domain name which is added in a hosting account features a number of records that enable it to function properly. In the standard 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 certain records created through the hosting company like A (IP address of the website/server), MX (email server), SRV (using a domain name for non-website purposes on a certain port number such as Voice-over-IP), etc. By having access to these records and by being able to edit them, you may have your website with company A and your e-mail messages with company B, for instance. This offers you more freedom since you can pick the best provider for every one of these services and you do not have to stick with 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 providers have an extra fee for this function.