Introduction to the Internet of Things

01 Definition

What is IoT?

The Internet of Things (IoT) is a network of physical objects, such as sensors, appliances, vehicles, and machines, that have built in electronics and software and can connect to the internet. They collect data from the real world, send it to other devices or to the cloud, and often receive commands back.

A complete overview of IoT

IoT compared with related terms

Timeline

1. 1982A soda machine at a university is connected to the network to report stock and temperature.
2. 1999Kevin Ashton uses the phrase “Internet of Things”.
3. 2000sCheap sensors, RFID, and smartphones spread. Connected devices begin to outnumber people.
4. 2010sSmart homes, wearables, cloud IoT platforms, and low power networks grow fast.
5. 2020sEdge AI, 5G, and the Matter standard make devices smarter and easier to connect.

02 How it works

How IoT works

An IoT system is usually built in layers. Data moves up from the device to the application, and commands move back down.

1. DeviceSensors and actuators with a small controller collect data and take actions.
2. ConnectivityWi Fi, Bluetooth, LoRa, or cellular carry the data, often through a gateway.
3. Data platformCloud or edge servers receive, store, and process the data.
4. AnalyticsRules and AI find patterns, detect problems, and make predictions.
5. ApplicationDashboards and apps show results and let people send commands.

Example: a smart room temperature monitor

1. Sense

   A temperature sensor measures the room every few seconds.

2. Send

   A small board such as the ESP32 sends the reading over Wi Fi using the MQTT protocol.

3. Store

   A broker or cloud service receives the message and saves it in a database.

4. Show

   A dashboard displays a live chart on your phone.

5. Act

   If the temperature goes above a limit, a rule switches on the fan and sends you a notification.

Cloud, fog, and edge computing

Key terms

Gateway

A device that connects local sensors to the internet and translates between protocols.

Telemetry

Data sent automatically from a device, such as temperature or battery level.

Broker

A server that receives messages and delivers them to subscribers, used with MQTT.

Firmware

The software that runs on the device itself.

OTA update

Over the air update. Sending new firmware to devices remotely.

Latency

The delay between sending data and getting a response.

Digital twin

A virtual copy of a physical object, kept up to date with live data.

Provisioning

Registering and setting up a new device with its identity and credentials.

03 Types and uses

Types of IoT and where it is used

04 Connectivity

Networks and protocols

Connectivity options

Messaging protocols

05 Hardware

Sensors, actuators, and boards

Common sensors

Common actuators

Popular boards

06 How to build

How to build an IoT project

1. Define the problem

   Example: “Tell me when my plant needs water.” Decide what to measure and what action should follow.

2. Choose sensors and a board

   For a plant monitor: a soil moisture sensor and an ESP32.

3. Choose the network

   Wi Fi for a home project, LoRa or cellular for remote places, Bluetooth for short range with a phone.

4. Wire and test the hardware

   Connect the sensor, read values, and check them on the serial monitor before adding the network.

5. Send data

   Publish readings with MQTT or HTTP to a broker or an IoT platform.

6. Build the dashboard and alerts

   Show charts and set a rule: if moisture is low, send a notification.

7. Secure it

   Use unique passwords, encrypted connections, and updated firmware. Never leave default logins.

8. Deploy and maintain

   Power it reliably, monitor battery and signal, and plan updates.

Starter code: ESP32 sends temperature with MQTT (Arduino)

#include <WiFi.h>
#include <PubSubClient.h>

const char* ssid = "YOUR_WIFI_NAME";
const char* password = "YOUR_WIFI_PASSWORD";
const char* mqttServer = "broker.hivemq.com";

WiFiClient espClient;
PubSubClient client(espClient);

void setup() {
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
  }
  client.setServer(mqttServer, 1883);
}

void loop() {
  if (!client.connected()) {
    client.connect("myDevice01");
  }

  float temperature = 27.5;   /* replace with a real sensor reading */
  client.publish("home/room1/temperature", String(temperature).c_str());

  client.loop();
  delay(5000);
}

Project ideas

07 Tool stack

Which tools are used for IoT?

Platforms and pricing change often, so check official websites before choosing.

08 Security and challenges

Security, privacy, and challenges

Security best practices

Main challenges

09 IoT and AI

How IoT connects with AI and other technologies

10 Career

Learning roadmap and careers

1. Month 1Basic electronics and Arduino. Read sensors and drive LEDs.
2. Month 2ESP32, Wi Fi, and simple web or MQTT communication.
3. Month 3Build dashboards with Grafana or Blynk, and set up alerts.
4. Month 4Learn networking basics, security, and OTA updates.
5. Month 5Cloud platforms, databases, and Home Assistant.
6. Month 6Edge AI with TinyML, plus a portfolio project with documentation.

11 FAQ

Frequently asked questions