Arduino is a small micro-controller device that was developed to help computer science students with their projects. It provides a software interface for writing the programs to manage the sensors and actuators as well as the power required. It has a number of advantages that include simplicity and powerful in terms of use, low in cost, cross-platform with OSs, open source in Hardware and Software. It is finding applications in systems used in different fields that include but not limited to industrial, medical, astronomy, instrumentation, military, transport, communication, entertainment and security among many other fields. Specific examples range from auto-drivers, auto-pilots, robot teachers, robot doctors and nurses, robot soldiers and wireless sensor networks. It is also one of the main device in layer one of the IoT system. This book describes the Arduino micro-controller as well as the sensors and actuators including the programs used to manage them. The book is divided into five chapters and the appendix. Chapter one discusses the Arduino board and the basic electronic components, chapter two is about sensors, chapter three deals with actuators, chapter four is about the transceivers and chapter five consists of up to eleven simple projects based on the components discussed in the earlier chapters. Appendix A is about how to access the online based simulator Tinkercad circuits that contains the virtual Arduino, sensors and actuators. Appendix B & C explain the use of the actual Arduino connected to the laptop or a mobile device. The final section D gives the recommended formats for lab report, project proposal and report writing. I highly recommend this book for starters who might have issues accessing the actual Arduino hardware and its respective sensors and actuators or have the it but don't know where to start from. Also, from this book one can be able to practice on how to use the Arduino, sensors and actuators based on the web based Tinkercad circuits software before venturing into the actual Arduino which might not even be necessary depending on the requirements. The other advantage of this book is that there is a seamless transfer of the programs written in it to the actual Arduino where one does not require to do new programs. After the actual circuit connection, which is a replica of the virtual circuit, just copy the program to the Arduino IDE upload and operations of the two will be similar. The book is also a perfect match for practical online learning more so during this time of Covid19 and even afterwards. About the author OTERI OMAE has over 15 years of electronics and telecommunication engineering experience in academia. He received a BSc Electrical/Electronic Engineering and MSc Electrical/Telecommunication Engineering degrees from JKUAT, Kenya, in 1999 and 2008, respectively. In the year 2000 he joined the industry to work as computer service engineer a position held up to 2002. In 2003, he joined JKUAT as a Teaching Assistant. Since 2004, he has been engaged in the teaching, research and development of different fields under Electrical & Electronics, Telecommunication, Computer Science and Information Technology in the university. He has published in conferences and journals under the areas mentioned including four books “The Signals and Things in IoT” from which much of the information in this book is extracted, “An introduction to digital electronics”, “Analogue Electronics with Operational Amplifiers” and "An introduction to analogue electronics". He is currently a lecturer in the Department of Telecommunication and Information Engineering, JKUAT, Kenya. His current research interests include AI application in Telecommunication and the use of different techniques for practical teaching.