Each domain which is registered and hosted has a lot of DNS records - some of them are created automatically when you host a domain, others can be created by hand if required. As an example, the A record of a domain name is its IP address i.e. this record shows where the website is situated; the MX records reveal where the e-mails are stored, while through an SRV record you can use a domain name for unconventional purposes, including a Voice-over-IP service. Being able to create and modify particular records permits you to have different services with different providers if, for instance, your current host provides dependable web hosting, but has troubles with the email service, or you simply prefer to get a particular service from a certain company. Although you can set up and modify these records freely and without any limitations as you own a given domain, many companies charge extra to give you this option.