Every single domain name that is registered and hosted has lots of DNS records - some of them are set up automatically when you host a domain, others can be set up manually if required. For example, the A record of a domain address is its IP address i.e. this record shows where the site is located; the MX records reveal where the emails are handled, while with an SRV record you can use a domain name for unconventional purposes, like a Voice-over-IP service. To be able to set up and modify particular records allows you to have different services with different companies if, for illustration, your present host provides dependable web hosting, but has difficulties with the e-mail service, or you simply prefer to get a certain service from a particular company. Although you will be able to create and edit these records freely and without any restrictions as you own a given domain, lots of companies charge extra to give you this option.