So there's a spot in the tower players can go to to post items that they have for sale and is divided up between weapons, armor, items and consumables. You cannot trade a lower tier item for a higher tier. So you can't offer Fatebringer for invective. Players go to the post and simply look for listings in the category they want. I want Suros regime so I go weapons>primary weapons> auto rifles> exotic. Then I find a Suros. I have 2 thorns so I offer one of those. On the other guys screen he has a green notification icon for the trading post. If that trade offer is there with no reply in 24 hours then it goes away. But the Suros owner looks the trade over and doesn't like it that much so he messages me and says Can you throw in a good scout rifle? I also have 2 visions. So I offer thorn AND vision of confluence. This is acceptable to offer a legendary because I am offering an exotic as well. Only 3 items can be offered in one transaction. The Suros owner likes this now and accepts the trade and puts his Suros in a vault of some sort near the trading post. Now a green notification appears on my screen so I can go confirm the trade. I then put thorn and vision into the trading post vault and confirm, then my items and his items switch vaults. The trade cannot go through until all items involved in the trade are in the trading post vault. Once the new weapon has a new owner, all the stats disappear and the player has to level the item up from ground zero. This prevents people from loaning out Max gallys to their buddies because odds are they don't want to level it up all the way for one Crota run. That's basically it. I probably forgot some details so if you have a question feel free to ask!