If an email is sent so that the primary addressee cannot see others copied, it is referred to as what type of copy?

When an email is sent with the primary addressee unable to see others who are copied on the message, it is known as a Bcc copy. This stands for "Blind Carbon Copy." The key feature of Bcc is that it maintains the privacy of the recipients included in the Bcc field. This means the primary recipient and any other recipients cannot see the email addresses of those in the Bcc field, enhancing confidentiality and privacy in email communications.

Using this method is especially useful in professional environments where protecting recipients' information is important or when sending out emails to a large number of people without disclosing their contact information unnecessarily. In contrast, "Cc" (Carbon Copy) allows all recipients to see each other, which could lead to information overload or privacy concerns, while group and visible copies do not specifically address the concern of confidentiality among recipients.