How to work on Enhancement Spots?

Hi Group,

I want to implement an Enhancement Spot ( in SE19 )...

I have go through some documentation to implement the same for our requirement , but I am not able to understand a few things:

1) what are composite enhancement spots? and is it necessary to specify this during the Enhancement implementation or not?

2) what actually happens during the implementation of an Enhancement spot and how is it different from a BADI?

thanks for ur help in advance.

Regards,

Vishnu.