How did they exchange good and service

The ancient Rome uses cart and boat to exchange good. The ancient Romans trade a lot of thing to satisfied their need (you could see the economy section). They even trade silk that was from far away china. That was considered a big feat because China was so far away. The ancient Romans uses their navy to protect the merchant ship from pirates. Most of their trade is internally (meaning they trade inside their empire). The ancient Romans depend on the import, because they live in such a luxury lifestyle and the Rome city can't grow enough food for its people. The emperor also provide a service called  bread line. The service is to provide food to the poor. Most emperor do this service to make it's citizen happy.