The in-game Trade system is used for the face-to-face exchange of items and gold in real time. This method is used primarily to avoid paying the fees associated with sending via Mail or listing through a Guild Store, as there is no cost to trade with another player using the Trade interface.
The interface for Trading can be accessed by approaching another player and using the Interaction menu to select Invite to Trade. Each player is given a small window on the left side for listing up to five item stacks as their contribution towards the trade. Items can be selected from your inventory on the right side; note that items cannot be drawn from your crafting bag and must instead be retrieved to your inventory before initiating the Trade process. Each player can also include a specified amount of gold as part of their offer.
When both players have added the items and/or gold they wish to offer, they each Accept the other's offer; when both players have accepted, the trade is complete and each player is sent the accepted offer of the other player.