In this chapter, we will discuss the Internet of Things (IoT) and how this emerging technological concept has changed network communication. This chapter will define what the IoT is and how it functions. Next, we will talk about how cyber security has changed because of the IoT. We will then move on to exploring the vulnerabilities of the IoT. We want the readers to be able to understand how botnets are being enhanced tremendously by the IoT. This chapter will also cover how the Mirai botnet has impacted network security. The next topics we will elaborate on are, the IoT's role in home automation, wearable devices, medical equipment, drones, driverless cars, and smart cities. After reading this chapter, the reader will acquire a solid understanding of what the IoT is and how it is changing the world.