What Are Web of Things?

The Web of Things (WoT) is an architectural approach and set of standards that extends World Wide Web technologies to physical devices and embedded systems, enabling smart objects to be discovered, described, and interacted with using the same protocols and data formats that govern web applications. Where the Internet of Things (IoT) connects physical devices to networks at the protocol and connectivity level, the Web of Things addresses the layer above: providing a uniform, standards-based means of exposing device capabilities as web resources accessible through REST interfaces and machine-readable descriptions. The WoT reduces the fragmentation endemic to IoT deployments, where incompatible proprietary platforms make cross-domain integration difficult, by establishing shared conventions for representing what a device can do and how to communicate with it.

The primary standardization effort is led by the W3C Web of Things Working Group, which published the WoT Architecture 1.1 Recommendation, defining the abstract architecture, vocabulary, and building blocks of a conformant WoT system.

Thing Description and Resource Modeling

The central building block of the W3C WoT framework is the Thing Description (TD), a JSON-LD document that serves as a machine-readable interface contract for a physical or virtual entity. A Thing Description declares the interaction affordances of a device: properties, which are readable or observable state values; actions, which invoke operations on the device; and events, which represent asynchronous notifications pushed by the device to interested consumers. By serializing these affordances as hypermedia controls, the WoT allows a software agent to discover a device's capabilities and construct appropriate requests without prior knowledge of its specific API. A smart thermostat, a weather sensor, and an industrial actuator can each expose a Thing Description, and a generic WoT consumer can interact with all three through the same programmatic interface.

Discovery and Linked Data Integration

WoT discovery addresses how consumers locate devices and retrieve their Thing Descriptions in diverse network environments. The W3C WoT Discovery specification defines a directory service architecture in which Things register their descriptions for query, and describes direct discovery mechanisms using DNS-SD and .well-known URIs for local network contexts. Semantic interoperability is addressed through JSON-LD annotations that allow Thing Descriptions to reference shared ontologies and vocabularies, enabling reasoning about device capabilities across heterogeneous deployments. Linked data principles, in which every resource carries a resolvable identifier and links to related resources, connect WoT descriptions to broader knowledge graphs, supporting applications that reason across physical sensing, geospatial data, and domain ontologies simultaneously.

Security and Privacy

The WoT Security and Privacy Guidelines, published as a W3C Note, enumerate threat models specific to networked physical devices: unauthorized access to actuators, eavesdropping on sensor streams, device identity spoofing, and denial-of-service attacks affecting safety-critical systems. WoT Protocol Binding Templates specify how security schemes defined in a Thing Description, such as API key authentication, OAuth 2.0 flows, and TLS client certificates, map to concrete protocols including HTTP, CoAP, and MQTT. Research on WoT deployments, such as the work on OpenAPI frameworks for the Web of Things published in the Internet of Things journal, highlights the practical trade-offs between standardized security profiles and the resource constraints of embedded devices, particularly in sub-GHz radio environments.

Applications

The Web of Things has applications in a wide range of fields, including:

• Smart home automation: unified control of lighting, HVAC, locks, and appliances from heterogeneous vendors
• Smart city infrastructure: integrating air quality sensors, traffic systems, and utility meters through common APIs
• Industrial automation: exposing manufacturing equipment as web resources for monitoring and remote operation
• Precision agriculture: connecting soil sensors, irrigation controllers, and weather stations within a common data model
• Healthcare: linking medical monitoring devices to electronic health record systems through standardized interfaces