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 company. On their end, three records are set up automatically when the Internet domain is added - one A record and two MX records. The first one is a numeric address, or IP address, that “tells” the domain name where its website is, while the other two are alphanumeric and they indicate the server that manages the emails for that particular domain name. The website and the email hosting are usually thought to be one thing, when they are actually two different services. Having separate records for them will allow you to have them with different providers if you would like. As an example, some new provider can have outstanding 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 to the former and MX records to have the e-mails with the latter, you could get the best of both providers. These records are checked when you want to open a site or send an email - either way, the service provider whose name servers are used for the domain name is going to 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 email will be delivered.