An option whose payoff at maturity is binary, depending on the spot price of the underlying ending up within a specific range (between two figures- upper and lower strikes of the option). Otherwise, the payoff is zero.

This option is double in the sense that it has two strike prices, and is digital or binary in the sense that it has two payoff scenarios: payoff is not zero (payoff >0) or it is zero (payoff = 0).

For example, a European double digital option pays a specific amount if the underlying price ends, at maturity, within the range defined by the upper and lower strikes.