Here's a simple way to think about how email address lines work for business emails:

To: The main audience. These are the people the message is intended for and who may need to respond or take action.

Cc (Carbon copy): People who should stay informed but are not the main audience. Think of this as an FYI list. If someone in Cc has information that would help everyone, they can use Reply All and join the conversation.

Bcc (Blind carbon copy): People who should receive the email without other recipients knowing they were included. Recipients in Bcc are hidden from everyone else and are not included in future replies unless someone adds them again. For instance, if you're sending an announcement to a large group, you might put everyone in Bcc to keep their email addresses private and ensure that replies are sent to the original sender only. Another common use is keeping a manager informed without making them part of the ongoing email discussion.