A swap is a flexible, private, forward-based contract or
agreement, generally between two counter parties to exchange
streams of cash flows based on an agreed-on (or notional)
principal amount over a specified period of time in the future.

If firms in separate countries have comparative advantages 
on interest rates, then a swap could benefit both firms. 
For example, one firm may have a lower fixed interest rate, 
while another has access to a lower floating interest rate. 
These firms could swap to take advantage of the lower 
rates.

Exchange goods & service , trade