The preliminary concept of IoT has been discussed in this section. Keeping the background of the readers in reference, the term has been explained in a simple way. The section consists of the subsections and the reader can make their own summary after reading all sub-sections. At the end, some suggested review questions have been introduced for learners to confirm the learning of the topic. The exercise is for self-confidence and improvement. The contents have been supported by illustrations and photographs for better understanding.