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.