In email, BCC stands for "blind carbon copy". When you put an email address in the BCC field, it means that a copy of the email you are sending will also be sent to that address, but no one receiving the email will be able to see the address in the BCC field. This is useful when you want to send a copy of an email to someone without revealing their email address to other recipients. For example, when you are sending an email to a large group of people who dont know each other, you can put their addresses in the BCC field to protect their privacy and make the email look like it has been specifically sent to them. Using the BCC field also reduces the likelihood that recipients will receive a spam message or a virus.