Unit 1: Computer System and Organisation (Chapters 1 to 4) It covers the basic organization of the computer system. It also includes the fundamental concept of Boolean logic and gates. Unit 2: Computational Thinking and Programming-1 (Chapters 5 to 14) It introduces Programming and Computational Thinking (PCT). It mainly concentrates on Phython language which includes fundamentals, decision making codes, iterative constructs, strings, lists, etc. Unit 3: Society, Law and Ethics (Chapters 15 to 16) It basically deals with general awareness of the society where the students can play vital roles to shape themselves. It includes ethics, cyber safety, social networks, awareness of accessing websites, cybercrimes viz. bullying, phishing, identity theft, etc. At last, it concentrates on gender and disability issues while teaching and using computers. A special care has been taken to explain the topics in lucid language. Each chapter contains adequate illustrations from simple to complex to make the topics easier. All the solved Python codes are well tested on the computer before incorporating in the textbook. In spite of our strenuous efforts, errors may remain in one form or the other. Students and the readers are requested to bring the same to our knowledge. We have tried our level best to give out of our knowledge to fulfil the need of the students.