A control system basing on the use of gestures and functioning especially in mobile terminals. The gesture control system is provided with a general purpose interface (320) with its commands for applications (310) to be controlled. The processing software (330) of the gesture signals includes a training program (331), trained free-form gestures made by the user being stored in the gesture library, and a recognizing program (332), which matches a gesture made by the user to the stored gestures and chooses the most similar gesture thereof. Gestures can hence be used as commands for controlling any application configured or programmed to receive the command. One and the same application functions in different models of mobile terminals without matching, and in a certain mobile terminal all applications can be run, which applications use specified interface commands. The application (310) can be e.g. a game or activity being included in basic implementation of a mobile terminal.