A spark plug having a front end of a spark plug body that projects over a front end of an insulator, a recess that is arranged at the front end of the insulator from which a center electrode projects and forms an air spark gap with a ground electrode, an annular intermediate space that is formed by the recess between the insulator and the center electrode, and a surface of the recess that runs in an at least partially curved manner between the center electrode and the end of the spark plug body so that the recess forms an insulating section that prevents a sliding spark between the center electrode and the spark plug body.