This book is a collection of selected papers presented at the Sixth Congress on Intelligent Systems (CIS 2025), organized by the Institution of Electronics and Telecommunication Engineers (IETE), Delhi Center, under the technical sponsorship of the Soft Computing Research Society, India, during September 6–7, 2025. The book covers high-quality research articles in the fields of soft computing, machine vision, robotics, computational intelligence, artificial intelligence, signal and image processing, data science techniques, and their real-world applications which are some of the recent advancements in real-world technologies.