The content of this Notes are highly useful for ESE - 2021 Prelims: Paper- 1: Information and Communication Technologies (ICT). It covers the entire Engineering Aptitude and Reasoning topics that a student appearing for any such examination should be conscious enough. The coverage of syllabus is as of latest trend. The theoretical part has been written in a lucid style for easy comprehension of the readers. Practice set provided after every unit for students to give a trial. All in all, the entire book is informative and impressive at the same time.