Whenever you add a domain as hosted in some account, you normally set a pair of Name Servers to direct it to that specific service provider. On their end, 3 records are set up automatically right after the domain name is added - one A record and two MX records. The first one is a numeric address, or IP address, that “tells” the domain where its website is, while the other two are alphanumeric and they show the server that manages the emails for that particular domain name. The website and the email hosting are often regarded as one thing, when they're in reality two different services. Having separate records for them will permit you to have them with different providers if you wish. As an example, some new service provider can have fantastic uptime for your site, but you might not want to switch your e-mails 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 could get the best of both providers. These records are checked when you wish to open a website or send an e-mail - in either case, the service provider whose name servers are used for the domain address will be contacted to retrieve the A and MX records and if you've set records different from their own, the right web/mail server will then be contacted and you're going to see the needed website or your e-mail is going to be delivered.