In recent years, the Internet of Things (IoT) emerge and have now become a topic of interest for general audience and academia, with applications covering almost every discipline in life. In an agriculture-based country like Thailand, for example, smart farming is the most famous IoT one would start with, from simple temperature and moisture regulation to advanced image-based plant monitoring and control. Of course, where there exist internet coverage, IoT development is limited only by your creativity. Manufacturing is another challenging domain that would benefit greatly from this widespread technology. The main purpose of this book is to serve as teaching aids for my IoT course at the Faculty of Engineering, Kasetsart University. ESP8266 and ESP32, from Espressif Systems (Shanghai) Pte. Ltd, .are selected as microcontroller hardware due to its low cost, ease of use, availability, and WiFi-equipped. On the software side, I choose NETPIE, a cloud platform developed by the National Electronics and Computer Technology Center, Thailand. The main reason is speed and reliability in this region and the service is free for basic usage. Readers elsewhere could easily adapt to other cloud services in your area. For some signal & system analysis part, I use Scilab software from ESI Group.