An e-mail alias is actually an e-mail that shares a mailbox with a completely different email. For example, you could have firstname.lastname@example.org plus email@example.com and messages sent to either one of them will be received in one and the same mailbox. This option will make it less complicated and much more convenient to control multiple email addresses since you will have to log into one mailbox if you work with webmail as well as set up just one address in a email app on your desktop. When you set up an alias, you won't just have the ability to get emails, but you'll also be able to send out e-mails from the various addresses and they'll share the Outbox, so you will have all communication in one location. Using aliases is surely a replacement for making use of various email addresses for various purposes or forwarding one e-mail address to another to be able to handle the emails of both in one place.