Gamma is the rate of change in an option's delta per 1-point move in the underlying asset's price. Gamma is an important measure of the convexity of a derivative's value, in relation to the underlying. A delta hedge strategy seeks to reduce gamma in order to maintain a hedge over a wider price range. A consequence of reducing gamma, however, is that alpha will also be reduced. Gamma, vega, as well as alpha, delta, and theta, are terms commonly used by options traders to describe the risk and reward of their respective option positions. These terms are often referred as the "Greeks," and characterize the degree to which the value of an option fluctuates in response to changes in observable parameters.
