Whenever you add a domain name as hosted in some account, you typically set a pair of Name Servers to point it to that particular service provider. On their end, three records are created automatically as soon as the domain address is added - one A record and two MX records. The former is a numeric address, or IP address, that “tells” the domain where its site is, while the other two are alphanumeric and they indicate the server that handles the e-mails for that specific Internet domain. The website and the e-mail hosting are generally thought to be one thing, while they're in reality two different services. Having independent records for them will enable you to have them with different providers if you wish. For instance, some new provider may have superb uptime for your site, but you might not want to switch your e-mail messages from your current host and by employing an A record to point the Internet domain to the former and MX records to have the e-mails with the second, you will get the best of both providers. These records are checked when you want to open a website or send an email - either way, the company whose name servers are used for the domain name will be contacted to retrieve the A and MX records and if you have set records different from their own, the right web/mail server will then be contacted and you'll see the needed site or your e-mail will be delivered.