IoT is a revolutionizing global platform of cyber physical devices, having applications in domains like home, defense, agriculture, manufacturing, smart city, smart grid system, and so on. The IoT architecture contains devices like sensor devices, network technologies protocols and standards, intelligent analysis, and intelligent actions. Sensors play a major role in IoT deployment. The second important architectural component is communication, which may range from thousands of kilometers to millimeter distances, like cellular NFC, SigFox, Thread, LoRaWan, and more. Protocol stack is needed for inter-device communication of sensor data, RFID, NFCIP, and ECMA are some of the protocols discussed in the chapter. The data collected through sensors needs to be processed and analyzed intelligently, and at the same time intelligent decisions are to be taken using some intelligent algorithms. The IoT has changed international research trends, even if it has some challenges related to sensor battery life and security as well as connectivity.