Each domain which is registered and hosted has a lot of DNS records - some of them are set up automatically when you host a domain, others can be created by hand if needed. As an illustration, the A record of a domain is its IP address i.e. this record reveals where the website is located; the MX records reveal where the e-mails are handled, while using an SRV record you can use a domain name for unconventional purposes, such as a Voice-over-IP service. The ability to set up and modify particular records permits you to have different services with different companies if, for illustration, your present host provides good web hosting, but has difficulties with the email service, or you simply prefer to get a particular service from a certain company. Although you will be able to set up and edit these records freely and with no limits as you own a given domain name, some companies charge extra to give you this option.