Acknowledging the importance of classification not only for library and information science but also for the study and mapping of the world phenomena, in this paper we revisit and systematize the main types of classifications and focus on the species of classification mainly drawing on the work of S. R. Ranganathan. We trace the evolution of library classification systems by their structures and modes of design of various shades of classification systems and make a comparative study of enumerative and faceted species of library classifications. The value of this paper is to have a picture of the whole spectrum of existing classifications, which may serve for the study of future developments and constructions of new systems. This paper updates previous works by Comaromi and Ranganathan and is also theoretically inspired by them.