Gold
Gold is currency of Idlescape. Many players call it GP, money, or coins.
Acquisition
You can obtain gold by selling most items to the in-game vendor, by trading with players on the marketplace, by opening chests, as loot from some monsters killed in combat, and by getting resources while affected by the Scroll of Wealth enchantment.
Use
Gold is used to buy items from the in-game shop and player driven marketplace. In non-ironman mode, most items can be bought with gold. Some notable exceptions are the untradeable Corrupted Ring and some event items.
Gold sinks
Some significant gold sinks are the Shrine of Toucan and the 5% fee on items sold in the marketplace. The in-game shop also removes some money from the game.
Gold in the Idlescape economy
The amount of gold in the game's economy and its distribution amongst players is known only to developers. Some endgame items are priced up to 5,000,000,000 gold on the marketplace.
Trivia
According to INFO, Habs is the richest player in Idlescape.
Monetary values appear white below 1 million, light green over 1 million, and pale blue over 1 billion.