We define the logit dynamic for games with continuous strategy sets and establish its fundamental properties, namely, the existence of a logit equilibrium, its convergence to a Nash equilibrium as the perturbation factor becomes small and existence, uniqueness and continuity of solution trajectories. We apply the dynamic to the analysis of potential games and negative semidefinite games. We show that in a restricted state space of probability measures with bounded density functions, solution trajectories of the logit dynamic converge to logit equilibria in these two classes of games.