What Is the Difference between a “Perpetual” and a “Fixed-Maturity” Future?

A Fixed-Maturity Future has a specific, predetermined expiration date, after which the contract is settled (either physically or in cash). A Perpetual Future (or Perpetual Swap) has no expiration date and remains open indefinitely as long as the margin is maintained.

The perpetual future uses a funding rate mechanism to keep its price close to the spot price.