
What is IOT ?
IOT stands for Internet of things. IOT is basically a network of connected devices which can collect the data and transport the data through internet without the need of human intervention.
IOT ecosystem consists of three main modules, they are Inputs, Embedded hardware and the IOT Platform.
The below figure shows the simple abstraction of the IOT Network.

The Inputs are the data collection devices or sensors.
These Inputs are connected to an embedded hardware kit such as ESP32 , Arduino or Raspberry Pi. The main function of the embedded hardware is to interconnect the Sensors and then transmit or receive the data through various interfaces such as WIFI, Ethernet or Cellular Network.
The data is processed by the IOT platform which has several widgets to visualize the data and control the sensors or actuators.
I will list out some popular devices for each module.
The Sensors could be temperature sensor, proximity sensor, etc.
The IOT embedded hardware could be ESP32, particle photon, arduino, etc.
The IOT platforms could be BLYNK, AWS IOT, IBM Watson, Microsoft Azure IOT, etc.
The protocol used to transmit and receive data is mainly MQTT.MQTT is the acronym for Message Queuing Telemetry Transport.
It is designed as an extremely lightweight publish/subscribe messaging transport that is ideal for connecting remote devices with a small code footprint and minimal network bandwidth.
The main features in an IOT Platform are the supported widgets.
The below figure shows the sample screenshot of the Blynk App IOT Platform,

The Widgets are basically the graphical user interface. There are 3 main types of widgets:
Controllers : UI elements used to send data to hardware. For example: buttons, switches, sliders, joysticks, etc.
Displays : UI elements used to visualize the incoming data. LEDs, Charts.
Interface elements : Special Elements to build user-friendly UI. Example: Tabs, Drop down menus, various inputs, etc.
What are the applications of IOT ?
IOT can be used in multiple domains such as Smart Home, Consumer Products, Manufacturing, Automotive, Logistics, Medical and Transportation.
Some of the use cases of IOT are Remote distribution transformer monitoring system, Remote Oil and Diesel Tank monitoring system, Smart Bus Seat Occupancy detection system, Pond monitoring system, Smart Locks, Smart Hotel Automation, Smart Home Automation, Home patient monitoring system, etc.