This book is written from the perspective of environmentalist and microbiologist work on a diversity of cellulose, cellulolytic microbes, their enzyme and its application. The aim of this chapter is to remind ourselves and other researchers working in related areas of cellulose and cellulases investigation of the enormous economic potential of the biodegradation of organic solid waste materials regarded as waste, and secondly to emphasize some of the modern approaches which give a broad outline of the current research position of cellulose and cellulase enzyme, and briefly refers to its applied fields.