An e-mail alias is an e-mail address that shares a mailbox with a different email. For instance, you can have email@example.com and also firstname.lastname@example.org and emails sent to either one of them will be received in just one mailbox. This option will make it much easier and more convenient to control a lot of email addresses since you will need to log in to just one mailbox if you work with webmail or set up just one e-mail address in a e-mail app on your PC. If you create an alias, you won't just be able to receive emails, but you will also be able to send emails from the different addresses and they will share the Outbox, so you will still have all communication in one place. Using aliases is a substitute for working with different email addresses for a variety of purposes or forwarding a single address to another so that you can manage the communication of both in one place.