Why and How to create RFC Destinations - please expalin in detail ?

Hi Friends ,

Can u please tell me

1. why we are creating RFC Destinations ?

2. How to create RFC destinations ?

3. don't we need RFC Destination for RFC Receiver Adapter ?

4. Only we need to create RFC Destination for RFC Sender ?

5. What are all the steps do we nedd in XI side and R3 side ?

6. in XI also do wee ned to use SM59 to create RFC Destination and R3 side also do we need to use SM59 to create rfc Destination ?

Can u please explain in deatil

Regards.,

Shyam