What are the major developments in classification systems over the past 2500 years?

During the early period, people were not able to similarize or differentiate between the characteristics of different organisms. In 1758 Carl  Linnaeus proposed a binomial nomenclature system. every single organism was given two names, i.e., genus and species. He then grouped genera into families- orders-classes-phyla-kingdoms. He also identified Animalia (animals) and Plantae (plants) kingdoms. 
Thomas Whittaker proposed a "five kingdom" system in which three kingdoms were added to the animals and plants: Monera (bacteria), Protista, and Fungi.
Carl Woese proposed a radical reorganization of the 5 kingdoms into 3 domains. 

An autotrophic protist - they can perform photosynthesis and mainly consist of unicellular algae. they can be divided into number of systematic group according to the shape of their cell and the type of photosynthetic pigments they use.