Whenever you add a domain name as hosted in some account, you typically set a pair of Name Servers to point it to that specific company. On their end, 3 records are set up automatically as soon as the domain 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 website is, while the other two are alphanumeric and they show the server that deals with the e-mails for that particular Internet domain. The site and the e-mail hosting are often perceived as one thing, while they are actually two different services. Having independent records for them will enable you to have them with different companies if you wish. As an example, some new provider might have outstanding uptime for your site, but you may not want to switch your e-mail messages from your current host and by employing 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 providers. These records are checked when you wish to open a website or send an e-mail - in either case, the provider whose name servers are used for the Internet domain will 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 e-mail will be delivered.