The presentation will give an overview of what Industry 4.0 means specifically for the steel industry. Starting from the technical core "Cyber-Physical System", the various aspects of Industry 4.0 will be presented: (1.) horizontal and (2.) vertical integration, (3.) end-to-end engineering and the (4.) human being as conductor of value chain. Then Industry 4.0 is interpreted especially for the steel industry and described along the steel production route. After units on the topics “Digital Twin” and “Big/Smart Data”, the lecture concludes with practical examples of Industry 4.0 in the steel industry.