Gamma vs Option Expiry

The rate of change of delta relative to a $1 change in the underlying price; highest for at-the-money options near expiry; long options have positive gamma; short options have negative gamma; high gamma positions are unstable and require careful management near expiry.

The date on which an options contract ceases to exist; at expiry, the option is either exercised if in-the-money (capturing intrinsic value) or expires worthless if out-of-the-money; for European-style crypto options (Deribit BTC/ETH), exercise is only possible at expiry, not before.