An email alias is actually an email that shares a mailbox with a completely different e-mail. For instance, you can have firstname.lastname@example.org as well as email@example.com and messages sent to either one of them will be received in a single mailbox. This feature will make it less difficult and more convenient to control multiple addresses since you will need to log in to only one mailbox if you are using webmail or set up one single address in a e-mail app on your computer. When you set up an alias, you will not only be able to receive messages, but you will also be able to send out emails from the different addresses and they'll share the Outbox, so you will have all communication in one place. Making use of aliases is surely an alternative option to using different email addresses for various purposes or forwarding one address to a different one to be able to manage the e-mails of both in one location.