You will understand the instrument most crypto volume happens in, why it never expires, and how a small recurring fee keeps a bet tied to reality.
Open any big crypto exchange tonight and look at where the crowd actually trades. It is mostly not the spot market from our first stop. Most of crypto's trading volume happens in an instrument traditional finance never had, one almost nobody explains from the ground up.
Picture a tug-of-war. One team bets the price goes up, one bets it goes down, and a referee keeps the rope level by charging whichever team is heavier. By the end of this stop, that picture is the whole instrument.
Traditional markets have sold this bet for centuries. Two sides agree today on a price for a future date, and on that date the bet settles against the real price. Farmers hedged harvests with it, traders speculated with it. It is called a futures contract.
Notice what the expiry date really does. Whatever the bet's own price does in between, on the deadline it must meet reality. The expiry is the anchor.
Crypto's twist was to erase the expiry. The same levered bet from last stop, but you hold it as long as you like, closing when you choose or when your margin runs out. A bet that never settles has a name: the perpetual swap. The perp.
BitMEX popularized the perp for crypto, and it took over the industry. But erasing the deadline erased the anchor. With no settlement date, nothing mechanical forces the perp's price to meet the real one. Left alone, the two prices would simply drift apart.
Here is the tug-of-war on the board. When the long team is heavier, their crowding drags the perp's price above the real one. Heavier shorts drag it below. The designers needed something that pulls a crowded rope back to center, automatically, with nobody in charge.
The fix they chose: every few hours, whichever team is heavier pays a small fee to the lighter team. Crowding now costs money, and taking the unpopular side now earns it. Before we name the fee, call the direction yourself.