How does an add-in work?

[B]

I want a detailed description of the following:
1)How the add-ins for an Outlook actually work?
2)How the Outlook is configured to incorporate the add-in?
3)How do you write an add-in?
4)What are the issues with using add-in(advantages and disadvantages)?
5)How does the usage of an add-in affect security of the system?
5)Are any of the add-ins for freely downloadable?

 

[Ken Slovak - [MVP - Outlook]]

Start doing your research at http://www.outlookcode.com/d/comaddins.htm