Each domain name that is registered and hosted has quite a lot of DNS records - some of them are created automatically when you host a domain, others can be created manually if required. For example, the A record of a domain name is its IP address i.e. this record reveals where the website is situated; the MX records reveal where the emails are managed, while using an SRV record you can use a domain name for unconventional purposes, for instance a Voice-over-IP service. Being able to create and modify particular records allows you to have different services with different providers if, for example, your current host provides dependable web hosting, but has issues with the e-mail service, or you simply prefer to get a certain service from a certain company. Although you can create and edit these records freely and without any limitations as you own a given domain name, many companies charge extra to give you this option.