When you add a domain name as hosted in some account, you usually 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 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 indicate the server that handles the emails for that particular domain address. The website and the email hosting are typically thought to be one thing, when they are in fact two different services. Having separate records for them will enable you to have them with different companies if you wish. For example, some new provider may have exceptional uptime for your website, 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 first and MX records to have the emails with the second, you could get the best of both providers. These records are checked whenever you want to open a website or send an e-mail - in either case, the company whose name servers are used for the domain name will 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 will see the needed website or your email is going to be delivered.