Suppose your email address is abc@gmail.com.
You have a practically infinite number of Gmail addresses. Just put a plus sign (+) after your name but before the @-sign and then type anything you like there, and the email will still reach you. You can also insert as many full stops (.) as you like , anywhere in the first half of your email address , and they’ll still reach you, too.
So for example you might give the email address abc+amazon@gmail.com to Amazon , the email address abc+twitter@gmail.com to Twitter , and the email address abc+KEYWORD@gmail.com to that other website you have an account on.