What makes Path of Exile different is the introduction of ‘currency loot,’ a feature completely unique to the game.
There is no base currency in Path of Exile. No gold, dollars, or money. You don’t kill a mob and see ‘361 gold’ drop. Instead, the currency is the drops thesmelves, which have other functions in addition to their purpose as economic bargaining chips. The lowest level of currency is the Scroll of Wisdom. You can find hundreds of these lying around very easily. The purpose it serves is to identify the rare gear you find on your journeys. Any item above the base rarity will drop as Unidentified, and you must use a Scroll of Wisdom to reveal the properties that it holds. The Scrolls of Wisdom are incredibly common, and in any late game map, you can expect to easily find at least twenty. They are worth so little that no one bothers trading them, and, after a point, most people don’t even bother picking them up.
Jumping up a few tiers in rarity, we get to the Orb of Transmutation. Once again, this is another drop that you can find anywhere in the game. When you find an item that has no stats on it, you can use an Orb of Transmutation on it. This bumps it from Normal up to Magic, and adds a property to it. This is extremely helpful if you find the item you need, but it doesn’t have any stats on it. You just throw an Orb of Transmutation on it, and now it has stats! As you get further through the game you can find Regal Orbs, which take that Magical item you made and bump it up even higher to become Rare. This adds yet another stat to the item.
As you can see, all of the currency items are not truly currency. Drops in Path of Exile are items that have and serve purposes within the game, typically modifying items. The players themselves have assigned value to these items, and use them to buy and trade other gear.
The Chaos Orbs is the widely agreed upon ‘standard currency,’ due to their relatively stable rarity value. You can collect Chaos Orbs, but it takes a while to gather a sizable stockpile, so you can buy Chaos Orbs directly in low price on GM2V, making them the perfect currency item.