What Is the Internet of Things? Core Concepts and Key Protocols Explained

01 What is the Internet of Things?

The term Internet of Things (IoT) was first proposed in 1999 and is considered the third wave of the information industry after computers and the Internet, now developing for over 20 years.

Today, IoT products are ubiquitous in daily life, such as smart home appliances and smart locks, representing mature applications of IoT technology.

The original definition of IoT is to connect all objects to the Internet via RFID and other sensing devices for intelligent identification and management, but its scope has expanded over time.

1. IoT is also the Internet

IoT is essentially the Internet for things; devices connect to the Internet, upload/download data, and interact with users. For example, a remote car‑starting app sends a command from a phone to a cloud platform, which forwards it to the car’s onboard computer, executes the start command, and records the operation.

2. The main entity in IoT is “things”

Unlike traditional Internet applications where humans produce and consume data, modern IoT applications have objects (sensors, devices) as both data producers and consumers. In smart agriculture, temperature sensors upload data to a control center, which automatically activates heating equipment when thresholds are crossed—no human involvement.

3. IoT and Artificial Intelligence

AI’s rapid progress is driven by hardware advances that shorten deep‑learning training time and the availability of massive data in the big‑data era. IoT devices generate huge amounts of data daily; after processing, this data can be used to train neural networks, which in turn improve IoT devices, creating a virtuous cycle.

IoT provides a valuable data source for AI, and AI applications can be deployed back onto IoT devices.

As major internet data sources become concentrated among a few giants, the still‑under‑exploited data generated by IoT devices becomes increasingly important.

4. Current Status and Outlook

With the arrival of 5G, IoT development is accelerating, and financing for IoT projects continues to rise. IoT applications span smart cities, smart buildings, vehicular networks, smart communities, smart homes, smart healthcare, and industrial IoT.

The heterogeneity of terminals and network architectures creates many niche markets, preventing a single dominant player and allowing many companies to survive.

IoT devices involve higher switching costs than pure software, making capital‑driven competition less effective; early movers can maintain a strong advantage.

Overall, the IoT sector remains a blue‑sea market where small companies can compete with large ones, and after the hype of AI and blockchain cools, IoT is likely to become the next growth engine.

02 Common IoT Protocols

1. MQTT

MQTT (Message Queue Telemetry Transport) was created in 1999 for a satellite‑based oil‑pipeline monitoring project. It is lightweight, supports QoS levels, low bandwidth, and can transmit any data type. MQTT uses a broker‑client architecture and a publish/subscribe model, providing three QoS levels and asynchronous messaging.

2. MQTT‑SN

MQTT‑SN (MQTT for Sensor Networks) adapts MQTT for sensor devices by running over UDP, adding a gateway that translates MQTT‑SN to MQTT and supports automatic gateway discovery.

3. CoAP

CoAP (Constrained Application Protocol) is designed for resource‑constrained devices, runs over UDP, and follows a client/server model similar to HTTP. It supports a small 4‑byte minimum packet size and an observe mode for subscription‑like notifications.

4. LwM2M

LwM2M (Lightweight Machine‑to‑Machine) is an OMA‑defined lightweight protocol using a RESTful interface. It runs over CoAP (UDP or SMS) and secures communication with DTLS. Its architecture includes a Bootstrap Server, a LwM2M Server, and LwM2M Clients.

5. HTTP

HTTP, widely used on the Internet, can also be applied to IoT devices with sufficient resources, such as Android‑based devices, enabling data upload/download and WebSocket communication.

6. LoRaWAN

LoRaWAN is a low‑power wide‑area network protocol operating at the physical and data‑link layers, addressing how devices connect to the Internet. It offers long‑range communication with low power consumption, and data can be forwarded to an IP network via gateways using protocols like MQTT.

7. NB‑IoT

NB‑IoT (Narrow‑Band IoT) also works at the physical/data‑link layer but runs on cellular networks, allowing devices to connect directly to IP networks without a gateway. It provides about 20 dB higher gain, enabling coverage in underground or hard‑to‑reach locations.

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