An e-mail alias is an e-mail that uses exactly the same mailbox along with the original email address. For example, you can have firstname.lastname@example.org as your original email address and add an alias email@example.com. The two addresses will be able to share exactly the same mailbox, so e-mails sent to both of them shall be received in a single place. You can use aliases for several needs, such as emailing numerous groups of people or registering on sites. If you start getting a number of spam, for instance, you can just delete the alias while your original mailbox will not be changed in the slightest and you will maintain the e-mails that you need. Aliases are often viewed as a substitute for forwarding e-mails from one mailbox to another one if you work with several addresses for contact on your website.