1) What are the advantages/disadvantages of add-ins versus VBA macros?

2) Will an add-in prevent others from viewing my code?

3) I have received an add-in from the net and was wondering if I could view
the code somehow? I would like to do this for two basic reasons. First, I
would like to confirm/verify that it doesn't contain any viruses. Second, I
would like to understand how it works.

Thanks in advance,

Christmas May