3D model of an Arduino IoT device.
Electronics are the backbone of all the modern wonders that we see, experience & thriving upon. Since the second industrial revolution, the field of electronics has envigorated the masses in one way or the other, helping them achieve great heights of success, without which would have been impossible.

An electronic circuit is nothing but a collection of discrete elementary components, along with some higher degree of complex and integrated circuits (ICs) to complete itself into a working electronic device.

An electronic device is designed and constructed to achieve a particular result of task(s) that can be otherwise rudimentary and complex to achieve manually.

Discrete electronics, sometimes referred to as passive components are the building blocks of basic circuits, while semiconductor-based components are referred to as active components as they can react to the way they are connected and interact with the input of electrical signals.

Advanced & integrated circuits (ICs) are a collection of these discrete electronic components and semiconductor components that hold together inside a manufactured package to be used just like any other electronic component.

Normally in a device, the circuitry is made up of discrete, active & integrated circuits to complete itself as a useable product solution. Digital devices are electronic circuits that operate under a specific voltage band(s) that is used for communication with each other, while analog or power devices are the workhorses that actually do the job as an intended end result.
    For example, in a classic case of a Water Level Controller, the control logic (usually Digital) uses sensors to find out the water level at both the overhead as well as in the sump and then sends a signal to run/stop the pump according to the user required set parameter, while it is the actual relay circuit that actually turns on/off the pump from the signal it receives from the control logic. Control logic operates in lower voltages that are safe for human contact, while the control circuit normally has unsafe higher voltages that need special care & expertise to work with it.
    If the same control circuit of the Water Level Controller is connected with the network of the user, it will be called as the Internet of Things (IoT), which could be monitored & even controlled remotely.