definition of tradin

1. Buying and selling securities or commodities on a short-term basis, hoping to make quick profits.

2. More generally, any buying andselling of securities, commodities, goods, or services.

or for example

i have new car and u have 2 cars
so we decided to i will give u my new car but have to give me the 2 cars instead of my car

trade on To put to calculated and often unscrupulous advantage; exploit: children of celebrities who trade on their family names.

trade up To trade something in for something else of greater value or price: The value of our house soared, enabling us to trade up to a larger place.