The concept of differentiation goes back to the seminal work on
monopolistic competition of Chamberlin (1933), who highlighted
that customers may have different preferences among available
products within the same industry. Along this line, Porter (1980)
later popularized the generic strategy of differentiation when
a firm creates something tangible or intangible that is perceived as
“being unique” by at least one set of customers. Thus, it is the
customers’ perceptions what determines the extent of product
differentiation.