Sometimes, I find myself wanting to notify a varied group of individuals of some event that affects them. However, because I serve the public trust, I do not necessarily want to broadcast to everyone involved the names of everyone involved.
Blind Carbon Copy would be as in e-mail. It would send a copy of the mail to the person in the BCC list, but not include their name as a record of the list of recipients (at least not for the other recipients). This would save me having to compose or forward a separate eve-mail for each party to preserve their privacy.