Any time you add a domain name as hosted in some account, you usually set a pair of Name Servers to direct it to that specific service provider. On their end, three 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, which “tells” the domain name where its website is, while the other two are alphanumeric and they show the server that deals with the emails for that particular domain name. The site and the email hosting are usually regarded as one thing, while they're in fact two different services. Having independent records for them will permit you to have them with different providers if you wish. As an example, some new company might have exceptional uptime for your website, but you may not want to switch your emails from your current host and by employing an A record to point the domain address to the first and MX records to have the e-mails with the latter, you could get the best of both companies. These records are checked when you want to open a site or send an e-mail - either way, the provider whose name servers are used for the Internet domain is going to 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're going to see the needed site or your email will be delivered.