The Internet of Things (IoT), in its essence, covers connecting a large number of devices (Things) to the internet (Internet). This is highly useful, as it gives devices on the ground access to the cloud, however it also exposes said devices to many threats and brings in more attack vectors to wherever the devices are installed. As a result, security should always go hand in hand when talking about IoT.
Background Building an Internet of Things project often relies on the well-established client-server architecture at scale. When the term was first used, it referred to users as the client, requesting to run jobs from a central computer, i.e. the server.  Nowadays, with IoT, clients are the edge devices requesting data to be stored/processed by a server. Although, in theory, a single server could handle a small batch of IoT devices, a sudden surge of device requests could easily overwhelm the server and affect availability and data integrity. This is where distributed computing coupled with a microservice architecture comes in.