This chapter provides a detailed review of case studies related to Industrial Control Systems, which are regarded as the backbone of industrial process management and its automation. ICS security and reliability are critical to operational success for the safety and efficacy of the distributed operations in many sectors. The case studies provide tangible learning points and demonstrate the practical application of ICS in various industries. The lessons learned are discussed, focusing on the challenges, approaches, and outcomes. Through these case studies, the chapter offers insight into best practices and methodologies for realizing optimal ICS performance and security across industrial domains. The results stress the need for a strong ICS structure and guide for the development of ICS in the future.