This book The Importance of English in Science, Technology, and Business is written to explain how English has developed throughout history, the significance of learning it as a Second Language, and the necessity of knowing Scientific and Technical terms. In the twenty-first century, English is the language of the Internet, of most scientific publications worldwide, of technology and of Business. The reader will find different exercises in Basic Mathematics and Geometry, Civil Engineering, Chemistry, Biology, Medicine, Computer Science, Business and a few videos in the chapters of English for Medicine, Computer Science and Business. This book is directed to university students who need to use precise and clear English for research papers, formal and business reports, resumes, and presentations. For the English teacher I include role play, dialogs, vocabulary, grammar exercises, discussion, comprehension questions of a few texts, group work, learning styles according to students´needs, writing activities with evaluation parameters, games to reinforce oral skills in business communication, reading strategies, and activities to be done before, during, and after watching a video.