This book constitutes the refereed proceedings of the 4th International Conference on Intelligent Technologies and Applications, INTAP 2021, held in Grimstad, Norway, October 11-13, 2021.

The 33 full papers included in this book were carefully reviewed and selected from 243 submissions. They were organized in topical sections as follows: Intelligence, Decision support systems, IoT; Robotics; ML and AI for Intelligent Health, Applications of intelligent technologies in Emergency Management; Smart Electrical Energy Systems, AI and ML in Security; ML and AI for sensing technologies, Social Media Analytics; ML in energy sectors and materials; and Miscellaneous.