Any time you add a domain as hosted in some account, you typically set a pair of Name Servers to direct it to that particular company. On their end, 3 records are created automatically the moment the domain address is added - one A record and two MX records. The first one is a numeric address, or IP address, that “tells” the domain name where its site is, while the other two are alphanumeric and they indicate the server that deals with the e-mails for that particular Internet domain. The website and the e-mail hosting are generally thought to be one thing, when they are in reality two different services. Having separate records for them will permit you to have them with different companies if you wish. As an example, some new service provider might have exceptional uptime for your site, but you may not want to switch your e-mails from your current host and by using an A record to point the domain address to the first and MX records to have the emails with the second, you could get the best of both companies. These records are checked when you wish to open a site or send an e-mail - in any case, the provider whose name servers are used for the domain is going to be contacted to retrieve the A and MX records and if you have set records different from their own, the correct web/mail server will then be contacted and you'll see the needed website or your e-mail will be delivered.