What is the purpose of the cc option in an email

CC is what is known as "Carbon Copy." When you cc someone they receive the email along with the original recipients, the original recipients may also see who you sent it too. For instance if I sent an email to Bob about a party, but I also wanted to invite Larry I would CC him (If you wanted to CC). Then Bob can see if he looks at who received the email that Larry was CCed the email. Larry when he receives the email will also see that Bob received it first.