Whenever you add a domain name as hosted in some account, you usually set a pair of Name Servers to point it to that specific company. On their end, 3 records are created automatically as soon as the Internet domain is added - one A record and two MX records. The former is a numeric address, or IP address, which “tells” the domain address where its site is, while the other two are alphanumeric and they indicate the server that handles the e-mails for that specific domain address. The website and the email hosting are generally regarded as one thing, while they are in reality two different services. Having separate records for them will allow you to have them with different providers if you wish. For instance, some new service provider can have superb uptime for your website, 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 former and MX records to have the e-mails with the latter, you can get the best of both providers. These records are checked when you wish to open a site or send an e-mail - either way, the service provider whose name servers are used for the domain address is going to 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 website or your e-mail will be delivered.