Any time you add a domain name as hosted in some account, you normally set a pair of Name Servers to point it to that particular provider. On their end, 3 records are set up automatically right after the domain address is added - one A record and two MX records. The former is a numeric address, or IP address, which “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 site and the e-mail hosting are generally regarded as one thing, while they're in reality two different services. Having separate records for them will allow you to have them with different companies if you would like. As an example, some new provider might have superb uptime for your website, but you may not want to switch your e-mail messages from your current host and by employing an A record to point the domain name to the first and MX records to have the e-mails with the second, you could get the best of both companies. These records are checked whenever you want to open a site or send an email - either way, the service provider whose name servers are used for the domain will be contacted to retrieve the A and MX records and if you've set records different from their own, the correct web/mail server will then be contacted and you are going to see the needed site or your e-mail will be delivered.