Any time you add a domain as hosted in some account, you usually set a pair of Name Servers to direct it to that particular provider. On their end, three records are set up automatically right after the domain name is added - one A record and two MX records. The former is a numeric address, or IP address, which “tells” the domain where its site is, while the other two are alphanumeric and they indicate the server that deals with the e-mails for that specific Internet domain. The website and the e-mail hosting are often considered to be one thing, while they're in fact two different services. Having independent records for them will enable you to have them with different providers if you want. As an example, some new company can have outstanding uptime for your site, but you might not want to switch your e-mail messages from your current host and by using an A record to point the domain address to the former and MX records to have the emails with the second, you could get the best of both companies. These records are checked whenever you want to open a website or send an e-mail - either way, the service 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 is going to be delivered.