The latest advancements in the manufacturing industry due to ICT (Information and Communication Technologies) has promoted the wave of Industry 4.0 in today's world. This has transformed the traditional mass-production model into the mass customization model. The vision of Industry 4.0 is to make machines that have the capability of self-learning and self-awareness for improving the planning, performance, operations, and maintenance of manufacturing units. This paper analyses the fundamental technologies behind the success of I4.0, namely Cloud computing and big data analysis, in great detail. The Cloud is the heart of Industry 4.0. It is the primary enabler of innovative, more efficient, and practical strategies in business processes by using artificial intelligence, intelligent sensors, and robotics. It has additionally examined numerous applications where this concept is being used along with various issues and challenges.