This book presents best selected research papers presented at the 4th International Conference on Cognitive Informatics and Soft Computing (CISC 2021), held at Balasore College of Engineering & Technology, Balasore, Odisha, India, from 21-22 August 2021. It highlights, in particular, innovative research in the fields of cognitive informatics, cognitive computing, computational intelligence, advanced computing, and hybrid intelligent models and applications. New algorithms and methods in a variety of fields are presented, together with solution-based approaches. The topics addressed include various theoretical aspects and applications of computer science, artificial intelligence, cybernetics, automation control theory, and software engineering.