What does BCC: mean?

BCC: meaning in Urban Dictionary

E-mail term. An acronym for "Blind Carbon Copy". BCC listsaddresses to which a note should-be sent, but which willnot be viewed because of the recipients.Supported by many e-mail systems, an ordinary, non-blind "CC" header could be visible to all recipients, hence letting them reply to each other in addition to into the transmitter. The addresses listed in a BCC header are not contained in the copies regarding the message sent to the recipients.