Overview of the different types of sunspot groups and the various observational parameters that lead to these 60 classes (white boxes). From a basic distinction between unipolar and bipolar sunspot groups, the unipolar groups can be classified according to the presence (or not) of a penumbra around the main spot, and the shape and North–South diameter of the penumbra. The classification of the bipolar groups is further subdivided by considering the internal sunspot distribution and the length between the two main portions of the group, and which portion has a penumbra (none, one end, or both).