An e-mail alias is an e-mail address that shares a mailbox with a totally different e-mail address. For example, you can have firstname.lastname@example.org and also email@example.com and emails sent to both of them will be received in just one mailbox. This option will make it simpler and much more convenient to handle multiple email addresses as you will have to log into one single mailbox if you are using webmail or create a single e-mail address in a email app on your desktop. If you set up an alias, not only will you be able to receive emails, but you'll also be able to send out emails from the different addresses and they'll share the Outbox, so you will have all communication in a single place. Making use of aliases can be a substitute for making use of various e-mail addresses for different purposes or forwarding one address to another one so that you can control the e-mails of both in one location.