You can use the To, CC (Carbon Copy), and BC (Blind Copy) boxes to direct a single item to any number of recipients. By specifying one of these three delivery types, you can indicate the response you expect from each recipient.
Use the To box to address the primary recipients of your item. Use the CC box to address recipients who have an interest in the content, or might require public notification of information, but are not expected to act upon it. Use the BC box to address recipients who have an interest in the content, but prefer to remain anonymous to the other recipients.
Everyone who receives your item can see a list of all the primary and carbon copy recipients, but cannot see a list of the blind copy recipients.