Perps vs spot vs dated futures
Spot is owning the asset outright. A dated future is an agreement to settle at a fixed expiry date. A perpetual future is a derivative that never expires — you can hold it indefinitely.
Because there’s no expiry to anchor it to spot, a perp needs another mechanism to stay tethered to the underlying price. That mechanism is funding.
Funding and mark price
Funding is a periodic payment between longs and shorts (often every 8 hours) that nudges the perp price back toward spot. When the perp trades above spot, longs pay shorts; when below, shorts pay longs.
Mark price is the fair-value reference an exchange uses for unrealised P&L and liquidations — typically derived from an index of spot prices, not the perp’s last trade. This prevents a brief wick on one venue from unfairly liquidating positions.
Leverage and liquidation
Perps let you apply leverage, controlling a larger position than your margin. The trade-off is liquidation: if the mark price moves far enough against you to consume your maintenance margin, the position is force-closed.
The practical workflow: choose your stop from the chart, pick leverage so your liquidation price sits beyond that stop, and check funding before holding across intervals. A leverage/liquidation calculator confirms the exact numbers before you commit.