When I apply my google account, I did not include my name in the user name. In some scenarios this might be not easy for others to recognize my email address like for example in the church’s mailing list. However I donot want another gmail account since it is too much to manage 2 email account. So the alias comes into play:
There are at least two ways you can modify your Gmail address and still get your mail. You can set up filters to automatically direct received messages to Trash, apply a label or star, skip the Inbox, or forward to another email account.
Gmail supports plus-addressing of emails. Messages can be sent to addresses in the form:firstname.lastname@example.org where extratext can be any string. Plus-addressing allows users to sign up for different services with different aliases and then easily filter all e-mails from those services. It does not appear, however, that the +string feature works when sending email from a gmail account to itself. Additionally (in some cases) the string appended to the e-mail address may not be longer than six characters.
The plus (“+”) sign is not simply a Gmail feature, but one of the valid characters in email addresses as specified by RFC-5233 (http://tools.ietf.org/html/rfc5233). Although it’s true that many email validation tools don’t take this into account.
Here is the step-by-step instruction on how to filter incoming emails using Gmail plus-addressing:http://www.wikihow.com/Use-Plus-Addressing-in-Gmail
2) Dot within username
Gmail doesn’t recognize dots (“.”) as characters within usernames, you can add or remove the dots from a Gmail address without changing the actual destination address; they’ll all go to your inbox, and only yours. In short:
All these addresses belong to the same person. You can see this if you try to sign in with your username, but adding or removing a dot from it. You’ll still go to your account.