Sixty years after the first magnetic flux compression experiments were performed, it is now appropriate to attempt a classification of the various devices that are known collectively as either magnetic flux-compression generators or magnetocumulative generators. This paper summarises the main characteristics on which such a classification of generators can conveniently be based, with emphasis given to the helical form that is undoubtedly the most common type of generator in use today. After indicating various fundamental limitations to generator performance, the paper introduces a number of features on which a possible classification can be based. Typical values are given for the major properties of the different features and the main applications are highlighted.