The study of classes with common characteristics; classification of artifacts; the systematic classification of artifacts or remains according to type, i.e. form and decoration. This is the first step in archaeological analysis and necessary in comparing assemblages and in determining time sequences. Groups of pottery, for example, may be assembled by those with long necks, those with handles, and those with a pedestal base. Within these may be sub-groups based on variations in handle shape or decoration. The relationships between similar types can sometimes be shown not merely to classify, but also to explain, their development - which is called seriation. It may show increasing complexity or functional improvement, simplification and functional decline, or change based on fashion. Typology may be associated with chronology, in that it may be possible to place groups of the same kind of material in a sequence.