Any time you add a domain 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 set up automatically when the domain address is added - one A record and two MX records. The former is a numeric address, or IP address, which “tells” the Internet domain where its site is, while the other two are alphanumeric and they indicate the server that handles the emails for that particular Internet domain. The site and the e-mail hosting are typically perceived as one thing, when they are in reality two different services. Having independent records for them will enable you to have them with different providers if you want. For example, some new company may have outstanding uptime for your site, but you may 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 latter, you can 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 company whose name servers are used for the domain address will be contacted to retrieve the A and MX records and if you have set records different from their own, the right web/mail server will then be contacted and you'll see the needed website or your e-mail is going to be delivered.