If you are a user of Gmail, then you might be surprised by what you can do with your email address.
Let’s say your email address is email@example.com. If anyone sends an email to firstname.lastname@example.org, or email@example.com or even firstname.lastname@example.org, it will all land in the same inbox. In other words, Gmail addresses don’t recognize the periods. You can insert periods randomly into any Gmail address and it will all end up in one place.
How can this be useful? If you have multiple accounts on a website and can only use one unique email address per account, now you have a way to “fool” the website. One account might have an email address email@example.com, another might have email address firstname.lastname@example.org, and so on.
By the way, the email addresses have been taken from my Spammers’ Hall of Shame.