Glossary
Perpetual Futures
A futures contract with no expiry, kept tied to spot via a funding rate periodically paid between longs and shorts. Crypto's flagship derivative.
A perp is a futures contract that never settles. To prevent the mark price from drifting from the index, longs and shorts exchange a funding payment every few hours: if the perp trades above spot, longs pay shorts; if it trades below, shorts pay longs. Funding pulls the mark price back toward the index.
Perps dominate crypto volume. BitMEX pioneered them in 2016, and they are now offered on every major centralized exchange and on-chain (dYdX, GMX, Hyperliquid).