This book gathers high-quality research papers presented at the 4th International Conference on Frontiers in Computing and Systems (COMSYS 2023) held at Indian Institute of Technology Mandi, Himachal Pradesh, India, during 16–17 October 2023. The book is divided into two volumes, and it covers research in “cyber-physical systems for real-life applications” pertaining to AI, machine learning and data science; devices, circuits, and systems; computational biology, biomedical informatics, and network medicine; communication networks, cloud computing, and IoT; image, video, and signal processing; and security and privacy.