The Web of Things (WoT) is software architectural styles and programming patterns that allow real-world objects to be part of the World Wide Web. Similarly to what the Web (Application Layer) is to the Internet (Network Layer), the Web of Things provides an Application Layer that simplifies the creation of Internet of Things (IoT) applications composed of multiple devices across different platforms and application domains. Differently from IoT which focuses on the Network Layer, WoT assumes that the connectivity between the devices is achieved and focuses on how to build applications. Rather than re-inventing completely new standards, the Web of Things reuses existing and well-known Web standards used in the programmable Web (e.g., REST, HTTP, JSON), semantic Web (e.g., JSON-LD, Microdata, etc.), the real-time Web (e.g., WebSockets) and the social Web (e.g., OAuth or social networks) This layer deals with the access of things to the Internet and ensure they expose their services via Web APIs. This is the core layer of the WoT as it ensures things have a Web accessible API, transforming them into programmable things. The access layer in the WoT is built around two core patterns: Firstly, all things should be exposing their services through a RESTful API (either directly or through gateway). REST is an architectural style at the root of the programmable Web thanks to its implementation in HTTP 1.1. As a consequence, if things offer RESTful APIs over HTTP, they get a URL and become seamlessly integrated to the World Wide Web and its tools such as browsers, hyperlinked HTML pages and JavaScript applications. Several designs describing how the services offered by things can be accessed via REST have been proposed.