Each domain that is registered and hosted has a great deal of DNS records - some of them are created automatically when you host a domain, others can be created manually if necessary. As an illustration, the A record of a domain name is its IP address i.e. this record shows where the website is situated; the MX records show where the emails are handled, while through an SRV record you can use a domain address for unconventional purposes, like a Voice-over-IP service. The ability to set up and modify particular records allows you to have different services with different providers if, for illustration, your current host provides stable web hosting, but has problems with the e-mail service, or you simply prefer to get a particular service from a specific company. Even though you can create and edit these records freely and with no limitations as you own a given domain name, lots of companies charge extra to give you this option.