Trading is a gifting type system on MovieStarPlanet. In other words, you give someone something and the other gives you something in return. Usually in trading you would make a look of someone and they could tell you what you could have. Then once they make a look of you and you tell them what they can have.
A lot of people like to trade for rares, or with rares. It is one of the most common trading on MovieStarPlanet. Most of the rare trading happens when someone has alot of rares which in someone (person) wants to get another one. However this is often a good scam to do in order to scam people of their rares, so be careful.