The term “hosting” does not describe just one service, but a variety of services that provide different functions to a domain. Having a website and emails, as an example, are two individual services although in the general case they come together, so most people think of them as one single service. In reality, each and every domain name has a several DNS records called A and MX, which show the server that handles each specific service - the former is a numeric IP address, which identifies where the site for the domain address is loaded from, while the latter is an alphanumeric string, which shows the server that manages the e-mails for the domain name. For example, an A record can be 126.96.36.199 and an MX record can be mx1.domain.com. Whenever you open a website or send an e-mail, the global DNS servers are contacted to check the name servers that a domain name has and the traffic/message is first forwarded to that company. When you have custom records on their end, the Internet browser request or the email will be directed to the correct server. The concept behind employing separate records is that the two services employ different web protocols and you can have your website hosted by one provider and the e-mail messages by another.