Zeny is the currency in Ragnarok Online. When things are denoted in "Z," that usually means Zeny, as in "Selling Item X, 100,000 Z!"
A single character is limited to holding (2^31 - 1) = 2,147,483,647 zeny at a given time. While engaged in a trade with another player, if either player attempts to add enough zeny to put the other player over this cap, the trade will automatically cancel. Additionally, a single trade is limited to 999,999,999 zeny at once. If you need to buy or sell an item worth more than 1 billion, you should contact trusted intermediary, such as the Game Management Team, to facilitate the trade.
If an item sold through the Vending skill would put the seller over the 2.1b zeny cap, the player buying the item loses their own zeny, they gain the item, and the player vending receives no zeny at all. Be careful when setting up a vend on characters near the max zeny limit.
Most players will limit themselves to either 2.0b or 2.1b on a single character at any given time, to prevent any accidental loss.
- Main article: Making Zeny
As Zeny is the main currency in the game, how rich a player is or how much gear and items they can afford is reliant on how much capital they have in terms of Zeny. Zeny mostly originates from selling items to NPCs, but selling to older players who already have large amounts of Zeny is usually the main method to attain decent wealth. The basics start with selling items to NPCs and Vending. Some items that have a high value can be hunted or obtained through Quests.