You can use multiple email addresses with your single Gmail account.
Trick #1
Suppose, you have your Gmail account as: firstname.lastname@gmail.com
With Gmail, you can also use it as: firstnamelastname@gmail.com or first.name.lastname@gmail.com or first.name.last.name@gmail.com
Gmail doesn’t recognize dots as characters within usernames. Email sent to all of these email addresses will go to your original Gmail account, that is: firstname.lastname@gmail.com
Here is what google has to say about this:-
Sometimes you may receive a message sent to an address that looks like yours but has a different number or arrangement of periods. While we know it might be unnerving if you think someone else’s mail is being routed to your account, don’t worry: both of these addresses are yours.
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:
homerjsimpson@gmail.com = hom.er.j.sim.ps.on@gmail.com
homerjsimpson@gmail.com = HOMERJSIMPSON@gmail.com
homerjsimpson@gmail.com = Homer.J.Simpson@gmail.com
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.If you get mail that seems to be intended for someone else, it’s likely that the sender entered the wrong address, just like if you’ve ever dialed a wrong phone number for someone. In these cases, we suggest contacting the original sender or website when possible to alert them to the mistake.
Source: Your address is similar but has more or fewer dots (.) or different capitalization
You may call it a feature or a bug. But Gmail basically allows this because your contact people might get mistaken with the dot in your email address. Suppose, your gmail account is firstname.lastname@gmail.com. Your friends might get confused with or forget the dot and type your email address as firstnamelastname@gmail.com. To remove this common human error, Gmail recognizes email accounts with and without dot to be as one.
Trick #2
Gmail does not recognize characters after the PLUS symbol.
So, if your Gmail address is firstname.lastname@gmail.com then you can also use it as firstname.lastname+blog@gmail.com or firstname.lastname+cool@gmail.com.
All emails sent to these address will go into your original Gmail address, that is: firstname.lastname@gmail.com
Trick #3
Suppose, your Gmail address is firstname.lastname@gmail.com. Then, you can also use it as firstname.lastname@googlemail.com
Email sent to firstname.lastname@googlemail.com will go into your original Gmail address, that is: firstname.lastname@gmail.com
Usuage
One big benefit of this Gmail feature is that you can now have multiple Twitter, Facebook or any other account with your single Gmail account. Because Twitter, Facebook, etc. recognizes dots as characters within email addresses.
It means that Twitter, Facebook, etc. recognizes firstname.lastname@gmail.com and firstnamelastname@gmail.com to be two different email addresses. But on the other hand, the email provider (Gmail) recognizes them to be as one.
So, create two Facebook accounts (one with firstname.lastname@gmail.com and the other with firstnamelastname@gmail.com). The confirmation email will be sent to your original Gmail address, that is: firstname.lastname@gmail.com. Confirm both of your Facebook accounts and enjoy!
Cheers :)